
That’s because trans men who are lesbians generally are not binary trans men. They may identify somewhat with masculinity, prefer masculine pronouns, or look/dress more masculine, but they may not consider themselves a binary man. Therefore they may feel that calling themselves straight would be inaccurate as they do not identify as a man who is attracted to women.
it's usually for people who aren't binary trans and still identify with the time they spent under the lesbian label. I'm unsure if your wording meant "makes you still a lesbian" as in doesn't disqualify you from identifying as a lesbian, or if you meant it as in more of an obligatory label, but just to clarify it would be that it doesn't disqualify you from identifying as a lesbian
like the whole masc/nonbinary man thing I get. but if someone actively identifies as a man and is not nonbinary. it just seems like it’s disrespecting their identity to include them in lesbianism?? bc lesbian = attraction to non-men and they ARE a man so shouldn’t we be kind and treat them like the gender they are??