You're not obligated to do anything. But people are also free to think you're an asshole for not respecting an incredibly basic request.

Not using someone's preferred name / gender pronouns is plain and simple being an asshole. Nobody really gives a shit about your opinions on being trans or whatever -- we've literally heard every argument you could possibly make many, many times. Just don't be an asshole so my day isn't ruined and I can pretend your outdated views don't exist.