OTOH, what about pre-operative Female trans in the men's locker room? Are they safe from males?
Probably not. But there is a difference here.
First, let's be realistic. Men are larger, stronger, and faster than women. Not every single man - you can find a tiny delicate man if you look for one. And not every single woman - female MMA Fighters exist. But 95% of the time, a randomly selected man can physically dominate a randomly selected woman. I don't like it - no woman I know likes it, despite porn seemingly insisting that chicks totally dig it. But we don't get to dictate to evolution, and we're a sexually dimorphic species.
So let's talk about why these are different scenarios.
If a female goes into a male space, that female is voluntarily taking risk on herself, by her own agency. She is likely to be outnumbered, and even if there's only one male in there, there's a 95% chance that if he wanted to harm her, he could do so... and there's nothing she could do about it. The key here is that the female is exerting her agency to take on risk to herself.
If a male goes into a female space, that male is imposing risk on the females in that space. He is not at risk from the females in that space - they are at risk from him.
In both cases, it ends up being the females who are subjected to the risk posed by the male. But in the first case, the female is voluntarily taking that risk, in the second that risk is being forced upon her without her consent.
When it comes to prisons, I am unapologetically biased. Any pre- or non-op transwoman belongs in a male prison or a separate transwomen's space, not in the female ward. Full stop. Post-op transwomen might be allowed in the female ward on a case by case basis, provided that none of their crimes were violent in nature, and none were of a sexual nature. And even then, the female prisoners should have the right to decline sharing a cell with that post-op transwoman if they so choose, because even complete SRS with FFS cannot change the physicality of a male. And a hugely disproportionate number of female inmates are there because they finally snapped and attacked or killer a man who had been abusing them for years. A massive number of female prisoners have histories of severe sexual and domestic abuse at the hands of men.
On the other hand... no matter how much testosterone or surgery they have had, I think that post-op transmen should NEVER be placed in a male prison ward. No exceptions. If there is a separate transgender ward, and they choose to be housed there, fine. But NEVER in the male ward.
Because no matter how much surgery, no matter how much hormones... males are still males and females are still females. Full penectomy and orchiectomy can remove the ability of a post-op transwoman to rape-with-a-penis. But no amount of surgery can make that transman the physical equal to the men in the male ward, and they will always be more vulnerable and more at risk in a male prison than any risk they present to women in the female prison.
