if you aren't cis then there's nothing to worry about

if you are, there's also nothing to worry about

Hey man, cis doesn't mean anything besides you identify with your given gender at birth. Just like male/female are useful terms for communication, we have a term for that. In fact, cis isn't even just for that. It's just Latin meaning you're in the same side of something. For example: cisalpine, meaning on this side of the alps (the side of Italy). No reasonable person would be offended by the term. It's been used for over 100 years in this way. The only reason to be offended is if you're told to be offended.

-sincerely: a cis-gendered man

How do you identify? What should we call you?

Turns me off as well, can't say why, but I can accept it.

You’ll be downvoted but people would do well to reflect on why. This is a large part of why white men didn’t vote, it’s why the “she’s for they/them he’s for you” was massively successful. I know in a just world we’d all be on the same page with this. But we’re not. You’re going to have to roll with this guy not wanting to be called cis if you want an ally and not an enemy.