Luckygirl3
I am absolutely happy for people to live the life they want to as long as they do so without harming others, but on a professional communication the writer's gender preferences are totally irrelevant to the matter in hand and have no place on these letters.
It might as well say: John Smith, likes jazz - it is nothing to do with the professional approach.
My DGC knows that their preferences are their own and they never get on a bandwagon forcing these into people's faces. They just quietly get on with their life. They have my support to be themself.
It's probably mainly for the benefit of people he works with. But rather than typing name out in full, he probably just does an e-signature with one keystroke, & it works for letters as well as emails.
So it's just a timesaving measure on his part, & I can't see it's offensive even if surplus to requirements.