I don’t think it’s a nit. It’s polite and proper feedback on the misuse of a term. The TL;DR here didn’t really convey anything useful from the rest of the post

I don’t think it’s a nit. It’s polite and proper feedback on the misuse of a term. The TL;DR here didn’t really convey anything useful from the rest of the post. So it ought to be rightly called “Introduction”, as you said.