I have never felt threatened by the idea of trans women in the loos. What I am threatened by is the idea of someone taking photographs or videos in them. JK Rowling supposed "defender" of women's safe spaces is actively making them less safe by encouraging this kind of behaviour
Quite easily, really. Decent men will stay out, as they always have, so we can assume all who don't are a threat, given their disregard for women's and girls' safety, privacy and dignity. Photographing, reporting and disseminating such men's images online will be a piece of cake.