> That logic would also state that we should no longer call a man a man if he becomes infertile through choice (or otherwise), no?
I don't think that's necessarily the case. The argument is less about individual cases and more about keeping the overall categories intact as traditionally perceived, which isn't really endangered in that case.
By the same argument, calling transmen men if they are passing perfectly would probably be fine. And that's likely what's been happening forever anyway, and is the point of "passing": those individuals don't threaten the general categories. It's a kind of "Don't ask, don't tell" policy.
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> > the lack of acknowledgment by trans activists that that's what they're doing
> I think that's because it's largely incidental
Is it? What you write about personal choice is all(?) true and does not contradict the argument.
My impression is that while transphobia is definitely a thing, a lot of the backlash against trans activism isn't about trans people's individual rights and choices but about trans activists wanting to impose certain beliefs that they have on others. For example, for the purpose of this discussion, the belief that the categories of "man" and "woman" must be defined differently than many (most?) people intuitively define them based on some of the most deeply rooted perception and pattern recognition of the brain.
So it may feel incidental to trans activists, but the people who react likely don't feel the same because it's the aspect (or one of the aspects) of trans activism that affects them the most personally.