the idea that restrooms, locker rooms, etc need to be single-sex spaces in order for women to be safe is patriarchy's way of signalling to men & boys that society doesn't expect them to behave themselves around women. it is directly antifeminist. it would be antifeminist even if trans people did not exist. a feminist society would demand that women should be safe in all spaces even when there are men there.
you cant ever let yourself forget what it felt like to be 15. how adults treated you. being treated without a shred of respect because people think youre too young to have thoughts and feelings of your own. the lack of autonomy. you cant ever forget that because if you do you might become the kind of adult who treats kids like theyre not people