Yeah, my plan for if I ever meet a “I don’t have pronouns” jerk in real life is to use neopronouns for them, because they’ll fucking hate that. I really like xe/xem/xyr, and I already have some practice with those. It would be hilarious.
(I want to be clear that if a non-transphobic person doesn’t use pronouns for real reasons that aren’t just transphobia, then of course I’ll do my best to not use pronouns. Like when I talk about the Public Universal Friend, I definitely try to avoid pronouns. It’s surprisingly hard though, a they or them is very likely to slip in somewhere.)