I've seen some people saying it's "transphobic" to talk about this, because it risks painting all trans women as potential threats.
But - the last time the whole "trans woman in male prison" issue came up, it was with Avery Edison, the comedian who went to Canada to see her girlfriend without the proper paperwork, and was (to nobody's surprise except hers) not allowed in, and the Canadian authorities held her in a male facility, although segregated from the men. There was a big internet campaign to correct this terrible injustice.
Now, Avery's crime wasn't in the least violent, and was probably down to a massive case of young, middle-class, white entitlement (how stupid and privileged do you have to be to think your paperwork doesn't matter at all when you go to another country, because, y'know, you are white and middle class, so why wouldn't they let you in anyway?), but Avery - young, white, middle-class, mostly-law-abiding, unthreatening, respectable Avery - is also the person who wrote about how their penis wasn't like a man's penis, and how transphobic you were if you treated it as such, and how hurt she was by the terrible transphobic woman she picked up in a gay bar, and who was happy to have sex with her, but not PIV. And Avery wanted PIV, and so she went to bed with her anyway, and then wrote a blog about what a terrible, terrible, no-good, hurtful transphobe this woman was for having enthusiastic sex with Avery but not allowing Avery PIV.
I wouldn't want any women to be obliged to share a prison cell with nice, young, middle-class Avery either.