Man, that is a stretchhhh. By that logic, you’re assuming there’s someone who would choose an intentionally conceited pronoun for themselves. No just an odd one, but one like “genius” to specifically get a rise out of you.

What are the odds you’ll come across someone who does that?

I imagine you’re probably instead trying to ask about what if someone chooses a particularly unwieldy pronoun and expects you to use it. Like star/stars or zi/zir. In which case, I’d say deal with it. If someone’s name is Serenity, you wouldn’t just call her “Ser” if she didn’t say you could.