If you are worried?
That's the point. You shouldn't have to be worried in the first place about this kind of thing.
You should certainly expect the other person to tell you this sort of thing beforehand.
I have the opposite view.
I think it is childish to think only of yourself when you are engaging in any sort of personal relationship with someone else.
It is childish to clean your hands of any responsibility you might have on hurting someone else's feeling.
By undisclosing something that has a considerable chance of being a deal breaker, and you know it, you are showing a huge lack of empathy.
But the cis-woman isn't necessarily thinking only of herself. They both want casual hook-up sex, so they consented to casual hook-up sex. That's the end of the transaction as far as both are concerned. In the days when I was young and wild, I had casual hook-up sex with a few people I knew absolutely nothing about, who knew absolutely nothing about me. That was part of the fun. Your imagination fills in the blanks. It's very romantic, especially when you're young and idiotic. Nobody is ever more appealing than they are when you barely know a thing about them and can imagine them to be spectacular.
Over-disclosure completely ruins the magic of the moment. Yes, of course there are associated risks. If you are concerned about the risks, just don't do hook-up sex. Get to know a person first, talk to them a bit, and if it turns out they used to be a man, gracefully extricate yourself from the situation.
You're basically arguing that a guy should be able to pick up random women in the bar and invite them home for casual sex, and it's the responsibility of the women he picks up to disclose anything that might make
him regret
his own choices. It doesn't work that way. He is 100% responsible for his own behavior, feelings and decisions.
I wouldn't give her a pass either, if
her feelings are hurt because he reacted in a bigoted way to the discovery of her birth gender. She is responsible for her own behavior, feelings and decisions too, including the decision to withhold her birth gender, increasing the possibility of his rejection or hostility after the fact, and any bad feelings she has resulting from his hostility.
My point is they both made choices that put them in this situation, and they are each responsible for their own feelings and choices. We can not be expected to take on responsibility for the feelings of people we barely know.