And you would think the tendency would be for homophobes to feel more threatened by gay or bi women than gay or bi men since the former demonstrate that at least some women don't really need a man for sexual gratification. Nevertheless, homophobes seem to be far more worried about gay men, generally speaking.
My guess is that Western homophobia is mostly rooted in the Christian notion that we are all basically morally rotten, and that only the thin veneer of civilization/religion prevents these horrible impulses in us from bursting forth. It's as if we each have our own inner child molester, yearning to be free, but in need of serious repression for the sake of Order.
So here you have a group of people in your midst, whose lifestyle appears to be a total rejection of what's regarded to be the most basic component of all civilization -- the nuclear family. And (gasp) they seem to enjoy themselves nevertheless. And surely one who rejects something so basic cannot be relied upon to support other essential civilized values.
That's my hypothesis anyway, -WD