Factors into the original question of:
Second question, since I can't really figure out my own view on it - should a trans post-op person still be morally obliged to tell a possible sexual partner that he or she is trans? Does it violate the other's right to know not telling it?
I really don't think so, in the one-night-stand/casual sex context. I mean, any sort of unexamined visceral disgust on my part towards trans people that I don't know about is far eclipsed by, say, dislike of Republicans or people with really bad taste in music. It's more one of those long-term relationship things, and I certainly tell anyone I intend to do sex with that I'm pansexual and non-binary, even though I appear to be a straight woman and had no intent of changing my gender presentation, simply because I've found in the past that
not saying so results in weird sexual expectations on my behavior. You know, gendered expectations.
Personally, even back when I was just straight-up identifying as a straight cis female and exclusively dating straight cis men, I'd have a regular conversation about gender roles and sexuality just as part of a getting-to-know-you sort of a thing. I really think that anyone, in any sort of long-term romancing relationship should do that, including all of the totally straight cis people out there. It feels like people get into a lot of heartbreak and domestic disputes later in the relationship due to not actually finding out whether they're compatible in that regard or not. It could save everyone a lot of pain.
Or, on another side: I need to not date blondes because of my PTSD. If someone dyed their hair, do they need to tell me if we're just going to have a one-evening thing? Absolutely no. That would be completely ridiculous, because it's not immediately relevant to the situation for me. An accepted risk of fucking someone you don't know is that you don't know them. If you think trans history is a no-go, then you should ask about that like you'd ask about any other such things (HIV status comes to mind, not that being trans is somehow a communicable disease. I've never had a one-night stand, so I don't actually know how much or what is talked about in those situations). Asking questions is part of producing the borderlines of your consent, and if you do not consent to sex with someone on grounds of minority status, it is your job to ask, not theirs to disclose. Your consent and your boundaries need to be produced and navigated by you. You cannot make someone else responsible for guessing what might or might not bothering you. That is a textbook abuse scenario, and asking a trans person to assume before any sexual encounter that their attentions are categorically unwanted is a demand that they think of themselves in a psychologically abusive way.
After all, there must be some reason why cis people feel like they don't want to disclose that they're cis, and don't like to assume that others wouldn't want them because of that at the start of every sexual encounter. It hurts, right? It's psychologically damaging. It destroys your ego. You just want to flirt and not especially worry about it. Creating social situations where people who have done nothing morally wrong must behave as though their very existence is assumed reprehensible creates a damaging, destructive society.
Again, one more time: Your preferences are your problem. When you treat them like other people are responsible for them, that is viciously entitled behavior and encourages abusive imbalances of power on the relationship level long-term. Have the conversations that you need to have, and make yourself personally responsible.
I just can't date computer programmers and atheists. It doesn't fucking work. So I start discussions about career plans and religion, as well.
And yes, I do reveal my mental health status early on in the relationship, before we get to the holding-hands stage, even though most of the time it results in my losing friends and being abused. I don't especially feel that it's my moral obligation, but it makes the relationship go slightly smoother.
This point of view that in order to not be bigoted you've got to be open to X Y or Z traits also leads people to doing stupid things like dating others to prove that they're not bigoted, which is really a negative consequence from my perspective. Dating is dating. You need people to be free to be openly themselves in that context more than any other one in life, and telling them who they
ought to be leads to folks struggling mightily against their own desires and natures. It's bad both from utilitarian and moral standpoints, so let's not do it.
Whether or not something is in someone's control is not the place to decide over whether behavior ought to be acceptable or not, by the way. One ought to be supported whether they chose to be gay or had gayness thrust upon them. It's inappropriate to disenfranchise people with fluid sexuality or gender because they didn't have the advantage of fitting into our ideas on whether "it's okay, because it's not your fault."
"We'd legislate the hell out of you, but as you aren't
choosing not to step in line with the bizarre aesthetic and social requirements of our morally bankrupt culture, we'll look past it and let it go."
A model of tolerance and equality.
I personally don't think any less of people who wouldn't date me because I'm non-binary or dyslexic or whatever either, by the way. People have preferences, some of which are very odd, and they should be allowed to have them. If you said "I wouldn't be
friends with you because you're non-binary," then I think you're an absolute ass. But: I feel like there's a habit of lauding people who want to have sex with you (even though that person may be a fetishist) and morally opposing people who won't (even though that person may be mentally ill or any other number of other things than Rankly Bigoted). I think it's fine to be biased when it comes to sex. You can't tell other people who they
ought to love, and looking down on someone for it seems really wrong to me. I found out that I'd been lusting after a Catholic republican, he disclosed his republican status to me, and I immediately lost sexual interest, went "nope," and walked away. This should be acceptable. It's ridiculous to act like I should have kept dating someone who voted for Romney despite a loss of interest, because that's way more important to me than how good he was at hilarious Kermit the Frog impressions or whether he was handsome. Similarly, one time I lost interest in someone early on because I found out that he was a heavy soda drinker. Something I wasn't expecting--something that had no bearing on him as a human being, really--but something that somehow changed his image, in a way I found bizarre. People with stringent requirements are going to have a harder time, but they're not somehow lesser just because of what they do or do not want.
People are often really shitty because of what they do or do not want, especially to minority groups who are already having a terrible time. But I think that, more than who we are or aren't fucking, we should pay attention to how people say and act in other contexts, because that's a much better indicator of how they feel about that group in general. If someone treats others well while quietly not dating people with trait X or airing those views outside of appropriate contexts, then what's wrong with that?
(Part of what's wrong with that is that for some reason people talk about how much they don't want to date someone trans one hell of a lot more than they talk about how they wouldn't want to date someone who loves birds or someone who doesn't share their hardcore love of almond butter. They also talk about it in places where it's kind of not relevant, like social policy threads, rather than keeping it to places where we're talking about the minutiae of what turns us on or off. I have never seen a discussion on PTSD derail to "I wouldn't date a person with PTSD," let alone receiving this much heated attention, because it was seen as wholly irrelevant to the topic at hand. Kind of like "whether or not you want to fuck a trans person" is wholly irrelevant to the question of social justice, whether your answer is yes or your answer is no.
That's personal, not political, and treating it as some sort of important political topic reminds me of the conversations that turn from talking about contraceptive access and anti-rape policy to whether or not women are morally obligated to shave their legs. I think we all know that that's ridiculous, so let's stop harassing a particular group about disclosing things, because they are no more obligated to do so than anyone else is to openness or honesty. It's almost like one group is being held to a standard which no one else is being obligated to meet and on which no one else is being questioned, and the group is being threatened with violence if they do not meet that standard. That seems more than irrelevant from a social-justice standpoint; it seems antithetical.
The same goes for questioning other people's self-identifications on gender and sexuality. If your gender is not being questioned as a valid identity--perhaps because it occurs with a high statistical frequency and is generally talked about and upheld by the culture--then it's not right to put other people's genders up on the block. That is not relevant to the aims of this thread, and pretending that your right to call others anything you wish is somehow not being protected when it is merely
off-topic is absolutely absurd. I reserve the right to call you a bigot and a jerk, but this is not the place to evaluate your particular moral outlook and condone or condemn you for them, just as this is not the place to examine the reality of my gender and verify whether it makes me fuckable or not. We're talking about ethics in general, not ethics as they pertain to some ant farm in a frictionless vacuum.)
tl;dr: The questions being discussed constitute a derail off-topic from the scope of this thread. Please re-rail and take personal discussions elsewhere.