I have no idea why you feel it is creepy for a woman to wonder what other members are female in a clearly majority male setting where it isn't possible to just look around the room and readily identify a few women visually.
I also have no idea why you are reacting so negatively to my footnote. People in the LGBT community often feel "left out" (i.e. discriminated against) when questions like this come up. It was only intended to suggest that, yes, I know the world is more complicated than the standard male-female dichotomy and I was hoping the question wouldn't turn into an excuse for someone to grind their favorite axe. If someone wishes to volunteer they are trans or some other category in order to scratch some activism itch, I don't care. All I am saying is that I am not intentionally excluding other categories and I respect the fact that most transgender people are better served by keeping that information private than by wearing it on their sleeve, which doesn't prevent them from being annoyed at being an invisible minority in such discussions. They are not invisible to me, but I don't care to spotlight them either and thereby cause trouble. I am aware I am treading on dangerous enough ground as is, with just inquiring as to who is willing to admit they happen to be female.
Furthermore, I am pretty sure there have been polls regarding religion which didn't cause any problems. So I find it odd that you think it would be nefarious to ask that question.