This is true. And I agree with you when you say if a rapist wants to rape - the sign on a door doesn't have a good chance at stopping that. But, by having a sign on the door, it's an additional hindrance, or safeguard. If you see a man in the women's room - you know something is up, even before they commit a rape/assault. If only women were allowed in women's rooms, it would immediately cause alarm if someone saw a man walking in there - which could indeed prevent something bad from happening. At the end of the day, it really boils down to what is more important - making sure that 0.3% of the population feels comfortable with what restroom they use, or preventing 0.3% of rapes from occurring because of the additional hindrances/safeguards. I guess this is a matter of opinion, but in my opinion, preventing the small amount of rapes than can be prevented is more important than making sure the small amount of feelings aren't hurt - but I'd be open to hearing opposing arguments on that.