I didn't say "straight men pretending to be transgendered", I said PERVS pretending to be trans. There is a BIG difference.
By "transwomen" you mean biological men pretending to be women, then yes, they should be scared to go into the women's restroom. Pervs are a threat and the potential prey (women) have the God-given right to defend themselves. Women can't overpower men physically, so they should be armed with some type of weapon to level the playing field.
If by "transmen" you mean biological women pretending to be men, I've seen one at my job and was startled at first because I thought she was a man. After my initial shock I realized she was a woman cross-dressing as a man, so I relaxed about it because I didn't see her as a threat. She was just minding her own business. I have a better chance to defend myself against a woman trying to molest me than a man, anyway. Also, I don't think she would feel safe using the men's room, I never saw her try to, and I would never tell her to go use the men's room, either. She's still a biological woman, so she uses the women's room. She has more sense than the "transwomen", quite frankly.
So if the woman dressing like a man still uses the women's room, why don't the men dressing like women want to use the men's room? Are they afraid something bad will happen to them in the men's room with all those scary straight men? Or could they be getting some kind of sexual charge out of using the women's restroom, like transvestite men get by dressing like women?