Re: Surely it's just a bit of civility
I instinctively refer to someone presenting themselves as female as 'she', and male presenting people as 'he'. If a woman in trousers tells me that she's a he then my brain struggles to remember this, and I would expect them to be tolerant.
When a man with a beard wearing a dress tells me that he's a xir then my brain rejects this idiocy. That's not bigotry, I'm perfectly fine with bearded people with male genitalia wearing a dress and I'm comfortable engaging with them in a private or work setting. I just can't do the linguistic gymnastics needed to use the word 'xir'.
The very rare person that manages to present themselves in an entirely androgynous manner leaves me in a state of utter confusion and lust.