Not disagreeing with you here, just trying to amplify on one point: I don't think it's really accurate to say that in previous eras "LGB were branded as pedophiles themselves." I think that charge/stigma was mostly or even exclusively aimed at the G, meaning gay men and boys.

Female sexuality was traditionally perceived and portrayed as quite passive, weak and anodyne compared to male sexuality, so even people who linked homosexuality to pedophilia didn't generally or necessarily see lesbians as a threat to children the way they might have seen gay boys and men. Also, females regardless of sexuality have never had a criminal or sexual offending pattern on par with males, so female people are generally not portrayed or feared as potential sex predators the way males are.

Growing up, most kids learn to be wary of the stock figure of the "dirty old man" and the kind of guy who hangs around parks and school nabes to wave his dick at kids or try to spirit them away to molest them. But we're generally not told - by adults or other kids - that there's a female equivalent of these guys. And for kid reason, coz there really isn't. Yes, some women are pedophiles. But most pedophiles and sex offenders are male.

For example, in Lillian Hellman's classic The Children's Hour (play version first published in 1934, William Wyler's movie version with Audrey Hepburn & Shirey MacLaine made in 1961), two women who ran a girls' boarding school were accused by a disgruntled student of having a lesbian relationship because she knows this will get the women into hot water - but neither the student or anyone else suggests that this could mean the teachers might have put a finger on any of the girls. The entire premise is that women perceived to be lesbians would be seen as inappropriate role models for teachers/heads of a girls' school - no indication is made, not even in hush-hush tones, that women who might be lesbians would go so far as to sexually prey upon their students.

As for bisexuals, I don't recall bisexuals across the board being demonized as potential child molesters the way gay males once were. I don't think bisexuals as a distinct group registered enough in the popular consciousness to get mischaracterized in this particular way.

At the same time, though, once greater awareness of the prevalence of child sex abuse began to dawn in the 1970s, there was widespread recognition amongst wide swathes of people of varying views - feminists, lesbians, gay males, homophobes, the religious right, therapists - that pedophiles are a) primarily males and b) commonly attracted to and will prey on children of both sexes. So some people might have linked bisexuality with pedophilia as a result.