For the purposes of this thread, the significance is that a woman who is in a locker room about to change into a swimsuit cannot tell the difference between cis or trans, gay bi or straight, but she can tell the difference between male and female.
And women are special in that regard... how exactly?
You could say the exact same thing about every other possible gender/sex/orientation/identification combination but... you can't because that would be homophobic or transphobic or if it's a man just scared of a woman just treated as adorably pathetic.
Again why are women the only ones allowed to present their discomfort toward being around other categories as fear?