An actual argument I’ve see on Tumblr is that people who are transgender can’t be/shouldn’t be bisexual, since doing so supports the gender binary.
Oh *Yawn* look More Biphobia! and mixed together with a little transphobia too. What a surprise, Not! They are very frequently found together, (see Mitt Romney 4 example). People interested in the topic might want to read this article about some of the roots of this disturbing phenomena.
Just why do these people think that the over one third or more of the the Trans* and Gender Non-conforming founders, current leaders and members of the Bisexual Community are supposed to listen to them anyway?
Being bisexual just means people who can ♥ people of same gender as themselves + can ♥ people of different genders/gender presentations from themselves. But when biphobic bigots ignore the bisexual community’s longstanding self definition and make up fake ones so they can attack them, tell me how are theses self-appointed identity police are any different than the anti-LGBTQ Str8 people who do the same?