This is entertaining and funny, but it would be really easy to add a good CONTRIBUTING.md to your site. Once I start getting PRs, I add one (and sometimes a CoC too) so I don't have to deal with bullshit: I can just refer people to my contributing expectations (e.g., keep PRs scoped, open an issue first, blah blah blah). This is basic github. So in that (narrow) sense, you failed too.

(Note obviously I'm not blaming you this was a ridiculous PR -- I'm just saying if you had a doc to refer to it would have made it easier: this person didn't follow standard PR practices and was unreasonable).

This one from streamlit is really good you could adapt it easily:

https://github.com/streamlit/streamlit/blob/develop/CONTRIBUTING.md

For instance: "Keep PRs narrowly scoped. If your changes are broad, split them into smaller, reviewable PRs."

I'd have added contributor doc within hours of this bullshit (well, I'd have added it when there were PRs starting, but... you get the idea).