Is it offensive to the LGBT community to call a man a butch?

For some context.

I have to write a story and in my story, there is a male antagonist that is supposed to be overweight with a baby face so bad you can't tell if he's a man or woman. I'm thinking of making the protagonist nickname him Butch to make fun of his features. I think this also gives the readers a clear image of what he looks like.

I just want to make sure it's not offensive like alluding to a butch being a negative thing etc.

Would appriciate if a member of the LGBT (perferably a lesbian) answers this :) thanks.