Know what though? There's no good reason it should bother me. Or you.
As Jesus said: "Whoever compels you to go one mile, go with him two."
In this case, just say "them," not "him."
So what if you or I think it's weird? I think "normal" ppl are weird all the time. I think I'm weird most of it.
What does it cost me to honor someone else's supposed "weirdness" with a word? What does it cost you?
Why do we care so much if someone's expression of gender is different? It's not like someone is taking your pronouns away from you.