I do kind of buy a lot of the objections to the segregation.
Yes, it's not fair that you're a male, and hence you as a non-violent male are at a risk of being locked up with violent males, unlike women. Those women with their unfair privilege of not having to go into men's prisons.
(And I'm thinking of any male here, nothing to do with trans).
But basic logic means we can't so easily segregate you as there's no objective marker. Best we can do is profile among males by history and current behaviour, and have different risk category wings, but that's not going to distinguish violence risk anywhere near as well as male-versus-female. And asking males to self-ID as "are you violent?" doesn't cut it.
Yes, things would be "more fair" if women also had to be locked up with violent males. But if you think that's improving the world you're a psychopath.
In effect we have multiple risk categories in prison - female, then various male categories. "Female" is the lowest risk category. And that's because of the objective measure that happens to massively determine risk. (In practice I understand prison systems don't need a "high-risk" category inside the female estate?)
And if you are seeking to get some sort of exception opened saying "well if I say I'm a non-violent male I should be able to get into the women's wing" I have no words for you. Either you're too stupid to realise that many, many violent males would take that up, or you just don't care.
You should no more be able to opt-in to that bottom risk category than you can opt into any of the others.
(And all of this is on basic risk category arguments, before you even start on any rights to female privacy or whatever...)