Conservative asked me my thoughts on a situation if a guy who says he's trans walks into a womens restroom but is lying and isn't actually trans

My thoughts is that it's a simple situation really. If they're harassing or assaulting people, the women will call the cops or something, simple situation and get the guy arrested. If he's not doing anything, it's nothing harmful. Apparently that's not a solid enough answer. What should I have said?