I don't think it's unreasonable to bring up consent, because it's not the sole element of an act's morality. It's one of many elements that go into working out exactly what a given act means. Consent is the difference between rape and one of the most pleasant things a human can experience, yeah. But applied to death, it's the difference between murder and a heroic sacrifice*, and both of those are considered bad things to have to happen, even if the latter can be said to be worth it.
There certainly is a lot of hypocrisy in how we treat entities that can consent**, but I feel like the meat industry is not hypocritical, even given an opposition to zoophilia, at least if the industry is compliant with the standards we've been talking about. Those standards are basically a claim that there are acceptable ways to kill an animal for its resources, but no acceptable way to abuse an animal (that is to say, cause unnecessary harm). The protracted suffering of nonconsensual sex and the payoff of orgasms, vs the fast and nearly-painless suffering of slaughter and the payoff of all the animal products, seems to me to create a very large gulf between the two scenarios.
The argument doesn't extend to humans because humans are assumed to be so valuable that murder is never worth that payoff, no matter how humane. Essentially, it seems like the claim is that the mind's inherent value is distinct from the value of the pain it can feel. The ratio of the former to the latter is assumed to be much lower in cows than in humans. If you don't buy that, then you won't agree with the conclusion, but it's still an internally consistent one.
*There's also suicide, which is the equivalent of masturbation in this analogy, and I'll admit that consent is crucial in that one.
**While I agree with most of your examples, the concentration camp thing is kind of odd. The people in the camps usually don't consent.
EDIT: tl;dr version. I think it's okay to say, "You can kill animals for resources, just don't be a dick about it." Zoophilia often falls in the category of "being a dick".