I s'pose they are disabled.
By the fact they don't want to accept biology, logic and scientific reasoning.
They aren't accepted to the toilets of their sex of choice, they don't want to go in the toilet of their own sex and guessing no one wants them toileting themselves in public, this is a compromise.
The disabled toilets tend to be single cubicles so they aren't bugging anyone else while they're in there and transgender people are so rare that if someone else who needed the loo came along, the wait wouldn't be too long. 