"Yes, seriously. You think people choose their sex?"
Wow, this is even getting more bizarre.
Um, whether people 'choose their sex' or not at conception is irrelevant to their preference after they are born.
You are losing the thread of your own argument. I stated that under a sex-based system, no-one gets to choose which facilities they use. You found this extraordinary, but in fact it's a natural consequence of the fact that no-one can choose their sex. Regardless of anyone's preferences, a rule that separates by sex is a system that does not allow for choice, because sex is not chosen.
This shouldn't be a struggle for you.
"Safety assessment is related but distinct. We can see the disparity by holding risk constant in both cases: trans-identified people under that policy have a choice that non-trans people do not."
Personal preferences are irrelevant to prison housing whose priority is safety not providing luxury resort satisfaction.
I agree that's how it should be. No-one, whether trans-identified or not, should be offered a choice of whether they enter the male or female estate. The fact that this is not how it operated in practice was wrong. In practice, trans-identified prisoners are given a choice that non-trans-identified people are not.
I don't know if you follow the news much, but when the Isla Bryson case blew up in Scotland, Nicola Sturgeon's explanation for why he should not have been in the woman's estate was, that he was "almost certainly not genuine". i.e., trans people have an option that non-trans people do not, and he'd pretended to be trans to access that option. This is a clear example of my "third case", i.e. "self-ID but only for trans".
Anyway -- putting my blocker on now as I need to get some work done.
If you do manage to come up with any example of the fourth case, you might make some headway persuading others on the board. So far, though, half an hour and several replies in and you haven't managed to give even one single example of the thing you claim is the general case.
I think you are someone who thinks that their beliefs proceed from the evidence and reason. This should be shifting your priors significantly.