I think he just meant that bi people feel more comfortable being in opposite sex relationships, and that's probably a symptom of how society treats LGBTQ people, at least that's how I read it. But he should definitely have been more specific, because it can be interpreted as bi people doing something wrong.
As for the tweet about trans people, I have no idea what he's on to. Sounds idiotic whatever it is.
Sometimes I wonder if David Miranda (his husband, who is a congressman and LGBTQ ativist in Brazil) has knowledge of some of the stuff he says.