I agree with this honestly, although I still think people can identify with whatever makes them comfortable, but your reasoning seems correct for why a binary trans man would identify that way. I've also heard of butch people and nonbinary people who go by he/him pronouns despite not identifying as a man and I think they are valid in identifying as lesbians.

I don't think it's 'lesbophobic' or 'transphobic' to come up for reasons why a binary trans man might want to identify that way, but I don't think it's an issue if trans men do identify that way and I don't think they necessarily shouldn't since labels are a very personal thing, but certain queer communities online can have some very, insecure reactions to anything they perceive as criticism of their identity and get very angry. It's best just to leave minor stuff like this alone imo.

I do agree that it is really harmful to inherently demonise straight identities though. There are plenty of trans people who are straight, and there are plenty of people in a spectrum of identities who don't identify with the label 'queer' or 'gay' or anything of the sort, and they are not boring or less trans or suddenly not discriminated against by cis and heteronormative society and you can still be non conforming while not being as queer or gay as possible, and you can still belong under the pride and LGBT identies, or are at least still allowed to be in those spaces, if you want to be. We aren't necessarily all united by identity, but we are united in a political sense.

Personally, I still identify as queer and a lot of 'straight' relationships I've been in I still see as queer, because I'm queer and most of the people I've dated have been queer, but I think in people's insecurity about their own queerness, any relationship that is perceived as straight can feel like it takes away from how they perceive their community and are therefore devalued. I just don't really talk to people in the community who devalue me or how I view myself or who are insecure enough to start arguments and call names over minor disagreements or differences in opinion.