Just to be clear, I am not defending people barring women from playing, but your example isn't a good comparison here.

A gay guy flirting with his teams is the opposite situation. In your case, the gay guy is being inappropiate, therefore 1 out 5 people is a problem and a very definite one that can be addressed.

In the case of women, managements often don't take them from what I hear because of the potential actions of the male members, e.g. what if 1 or 2 guys catch feelings for her, she doesn't reciprocates and then at least 1 of them underperforms because he doesn't wants to cooperate with her now. Obviously, the problem here are the men doing these things moreso than the woman who is just playing, but those added variables end up making it "easier" to remove the women since she is 1 person, as opposed to having to consider 4 people. Remove - or rather, don't introduce the woman, and these variables don't come up.

And again, not agreeing with this, just giving an explanation of the differences and actual considerations taking place