You are so close to getting it. And yet, so far.
The point is that language needs to have meaning. There need to be words for different biological sexes and different sexualities which are defined according to objective criteria.
If some biological females who are exclusively sexually attracted to other biological females want to have a word for themselves, which only refers to them and does not include any biological males or any biological females who are attracted to biological males, they are entitled to do so. Until about five minutes ago, the word for that group of people was "lesbians".
All biological males and all biological females who are attracted to biological males - whether they are also attracted to biological females or not - should respect lesbians' right to have their own word by not using the word "lesbian" to refer to themselves and coming up with a different word to describe whatever it is they believe they are.
By using the word "lesbian" to describe themselves, they are failing to respect a boundary that lesbians believe should exist.
Self-identified "lesbians" who are either trans women or women who would consider dating trans women, and who say that everyone gets to decide how they define their sexuality are not trans inclusive lesbians. They are non-lesbians who have decided they wish to use the word "lesbian" to describe themselves.