[akvadrako]

I'm not sure what the main reasons for segregating by bio sex were, but I can think of a few and none apply to gender identity.

Maybe the most important is you don't want prisoners getting pregnant.

[endori97]

Men in prison are also massively stronger and build shanks out of everything. If you do have a fight break out, hopefully its segregated by sex, otherwise the woman has no chance in the supermajority case.