I have a real problem with this - you're basically saying that someone who is trans is neither male nor female. If I identify as a lesbian, and I date a trans woman, I'm still a lesbian because a trans woman is a woman. By saying that there needs to be another sexuality to describe people who date trans people, you're invalidating that trans person's gender. That's not okay and you should really spend some time thinking about that.
I've at no point said that an individual can't use it to describe themselves, just that I would prefer it was a word that wasn't used around me and I think that…