I think you put your finger on it, actually: we don't talk about queer stuff, not openly. We might hint at it, if we feel particularly daring, but to come out and say it--that's just not done.

And I think there's a sense of "You can't accuse people of that!" that goes along with it, especially for those people who (by our standards) were not out and proud--if it's possible to claim that a figure was passing as straight, then it's possible to just go ahead and claim that figure as a straight person. So by just not talking about queer things, we cloak queer figures in a quasi-heterosexual patina that then gets assumed to be genuine, and yeah. It's depressing.