There's no biological imperative leading kids to develop hormonal urges to use firearms (unless they've Republicans).
The argument "Look, kids are eventually going to have sex" has validity.
The argument "Look, kids are eventually going to shoot an Uzi" does not.
Disagree. I think it's just as much inherently human to be curious and want to touch and figure out intricately designed tools as it is to have sex. Tool use and figuring out puzzles are right there at the core of the human condition, hand in hand with things like sex.
And then on TOP of that, add in
another core human desire to imitate role models and play make believe, plus the ubiquity of guns used by heroes in half of our media and stories, and you have yet another deep urge to play with guns when encountered.
"9-year girl accidentally impregnated by sex instructor in accident"
Pretending that analogies are just trivially not a real thing, or useful, or that they have to be 100% PERFECTLY alignable (which would make it
not an analogy anymore...) is a tedious and poor route of argumentation. The biology thing is reasonable, because it strikes at the core of the analogy along the dimension that is being compared and that matters (although I think it's wrong, as mentioned above). This is just grasping at straws, though.
There are obvious casualties to sex ed all the time. Namely, if you give a person incorrect information, and then they go use it while having sex with somebody and get a disease, then they can die or be made sterile or all sorts of things as a result. Just like gun training can have casualties. Requiring that it be literally the instructor involved to be valid is just trying to obnoxiously derail and distract, and you know it.