someone assuming the label of trans purely as a way to get what they perceive to be an easier time in prison

In what world do you envision someone can be sick and twisted enough to molest a child, rape a woman, expose himself to complete strangers, ejaculate on people in public, etc. but not twisted enough to tell a lie in order to exploit a system that says "anyone who identifies as a woman will be locked up with women"? Men have been known to impersonate gynecologists, to gain entry into the priesthood, to become accredited in education, all so they can access potential victims. Why the hell would you think someone wouldn't do something similar when it comes to a place where he can be literally caged with a woman, and undress and shower with women?? What better place could that person spend his time behind bars?

It's simply not true. Two well-known examples:

Karen White: committed multiple rapes while a free person, got locked up in women's prison, and simply recommenced the rape spree.

Princess Zoee Marie Andromeda Love: convicted of raping a 12-year-old girl. Sent to women's prison, and raped a developmentally disabled inmate who was already a survivor of sexual assault and was supposed to be in the prison’s mental-health unit. While it's stated that Princess got a haircut and started saying "I'm a man" upon release, thereby upholding the argument that this was not a real trans person, it still raises the argument I originally proposed to you and anyone else who defends mixed-sex prisons address: what's to stop any other sex offender from exploiting the system in the same way?