Links to the “campaign” please. Such a successful campaign run by gay activists that shaped how the world views bisexuality - must be tons of stuff in the media, pamphlets flying off the gay press, social media buzz, maybe medical articles from the gay medical establishment? Let's see it. Cos it's strange that I've lived all my life among gay men and women and don't think I've heard a single one deny the existence of bisexuality.
I think the mistake he's making, is that when he says "Bisexual men are still largely seen as gay men passing as straight." He's conflating that some gay men do indeed start off the coming out journey by initially claiming the bi label, that is what I read from his later arguments to some extent, and the other part was not appreciating how many different factions and flavours the LGBT rights' movement (just like every other civil rights movement had, Malcolm X/Martin Luther King, look at all the different varieties of feminism that were out there etc) had. There were huge amounts of different strains of thought, it was disingenous to put such a hefty focus on gay men. It is true that some gay men do their coming out journey that way, but I think it shows an unintentional lack of understanding for gay men's experiences on his part.
The hardest part of self-realisation for myself was admitting same sex desire, so that's why I told a handful of people at a point where I frankly wasn't yet ready to come out yet, and still mainly in the closet that I was attracted to men, but not ready to embrace the gay label. I had got over the self-realisation of homoerotic desire, but wasn't ready to accept myself Not all of us are able to make the leap initially when we are younger, and the thing is being in your late teens and early twenties. That does tend to be a point of your life where you massively care about what other people think of you, so you are looking for any perceived "softer" landing into it, before making the next leap later to say you are exclusively attracted to men. I'm not suggesting by that, that it is any easier to be bisexual than gay as a man, nor that it is easier to come out as gay or bisexual as a man.
But I think if he has come across a few gay men thinking that way, of course it is because they are falsely conflating their life experiences with his. But even that tends to be done (though probably not in all cases) on a case by case basis, not as a blanket preconceived notion that there are no male bisexuals, which is how he infers it (I've never met a gay guy that suggests that personally in my life). I personally didn't initially have the guts that someone like
@MisterB had. I did that because intuitive straight friends of mine picked up a vibe from me, and tried to coax me out the closet at a point where I wasn't ready for it. I think they were well meaning and empathetic, but didn't quite grasp how challenging that was for me. Dante's old line: "The road to hell is paved with good intentions". I personally made the leap to confess my true orientation three years later and came out to everyone, If I could turn back the clock, I would have just said to that straight friend when I was 19 and deeply closeted, "yes, I am gay. But I need to come out in my own time. I am not yet ready for it." Perhaps, there are straight people out there that witnessed a similar coming out progression from gay men they've known on a personal level, and conflate that to be the case every time. But gay men who do do it this way, are not doing it to deny bisexual men's sexual reality or the genuineness of their identity. I do frankly feel a bit guilty, if that is the way it comes across. And frankly I've seen way more straight people jump to rush to the conclusion that a man is gay, if they see him fooling around with a guy, than I see with gay people. I've seen this happen to male friends and colleagues of mine, the others weren't entertaining the notion that they were either experimenting or bi. If you see some straight people doing this, frankly it's their fault. I can apologise for doing it the way I did to a certain extent, but I'm not taking responsibility for a straight person (or anyone else for that matter) seeing my experience and projecting that onto another man's experience. That is their business.
Another factor that I think he is ignoring is the impact of toxic masculinity. This is highly wound up with homophobia and also bisexual erasure, when it is directed at men. Homophobia is often a large part of this. A man does this, a man must be aggressive, a man must treat women like sexual conquests, a man must never sleep with men, a man must not show his emotional side.
@Phil Ayesho this isn't something gay men did, this is something straight men did and a heteronormative society endorsed it. We come off on the rough end of this as much as you do (because we both experience homophobia), and even straight guys come off on the wrong end of this sometimes too (though usually for other reasons). This is the main reason in my opinion, why non-heterosexual orientations in men, get treated differently than they do in women's cases. It is keenly related to gender stereotyping. As has been stated beforehand, perhaps the reason why it is easier for bisexual women to be accepted, is that F/F sex is fetishised by a lot of straight guys. I honestly think you are ignoring the role toxic masculinity plays in this, and that impression comes from how much of a focus you are placing on gay men for this. But also, having known both lesbians and bisexual women in my social circles, I've seen that hurt them too. So many female friends of mine who are LGBT, talk about how unpleasant it is when they see a straight woman that they're really into, show some interest solely to get a straight man's attention. They might be accepted as being bisexual in a way more than bisexual men are, but I have seen them feel extremely hurt because they're feeling like being toyed with for selfish reasons.
I can empathise with you on why you feel so frustrated on being dismissed. It is wrong. But don't dismiss another LGBT man's experiences, the vast majority of us welcome you into our big tent as equally valid members of the LGBT community. Like
@MisterB said we keep adding letters to the acronym to try to display that everyone is welcome.