What do you think actually happens in exchanges? Are you imagining some sort of scenario where a trans lesbian walks up to another lesbian and demands sex? This is so bizarre. Why would you think that would happen?
I don't have to imagine. I have been told in face-to-face conversations with lesbians about the general unpleasantness as well as coercion, threats and actual violence they have experienced at the hands of male transgender individuals whom they turned down. Not shouting about it. Politely. It didn't matter. Their words didn't matter. Their tone didn't matter. Their behaviour didn't matter.
The only thing that mattered was that they said no. For some male people, regardless of how they identify, a woman's no is an invitation to abuse.
I've communicated with even more lesbians, some of whom I met IRL afterwards, all telling the same upsetting tales of being expected to include male heterosexual transgender people in their dating pool. And of being ostracised from their own communities when they fail to comply. Some lesbians do try, and when they find that biology wins out, they are simply punished later for realising they really are exclusively same-sex and not same-gender attracted.
I've also met older lesbians, middle-aged plus, for whom this is something they only hear about from younger lesbians. But even many of them will tell you how keenly they feel the loss of lesbian spaces. And how the male transgender heterosexuals who were drawn to lesbian spaces when they were younger were tolerated (mostly ignored) in those spaces, but they never liked them being there. Not that most of them said anything. That those heterosexuals now have such power and influence in the spaces of younger lesbians saddens them greatly.
I think you have to be wilfully blind by this point if you're denying that this hostility towards exclusively same-sex attracted females exists and is acted upon. I mean some of it happens very publicly, like what Magdalen Berns went through at Edinburgh University.
So sexual orientation is different from other characteristics, but I would say the same approach is reasonable. So if a straight man was approached by a gay man I think they can easily say 'Sorry mate, I'm not interested', rather than saying 'Sorry mate, you've got a dick and balls and that's a real turn off for me', or if a straight woman was approached by a gay woman, she could say 'Sorry, I'm not interested' rather than shouting out 'God, no, I'm straight, your vulva is really unappealing to me". They are acting according to their orientations without going out of their way to say something that might be hurtful to others.
So, "no thanks" is okay, but "no thanks, I'm gay" is not okay? Coz one ought not to disclose one's sexuality when turning down an interested party?