If I was a woman (or girl) and saw a guy in the ladies’ room or ladies’ changing area/locker room I’d run out screaming “pervert”.That’s the way to solve this.
What bathroom should this woman use?
The photo above contains two biological females in the ladies' room.
Maybe — point and laugh.
Sadly, that would probably just set you up for a lawsuit. Slander or infliction of mental anguish or some such nonsense.
People like this have nothing better to do (if they did, they wouldn’t be spending so much time contemplating what gender they might fancy today), so filing lawsuits is a major pastime for them.