As an open source maintainer, when someone opens a PR, I don't know who they are. But I don't really care. I care about the PR: is it a "good" PR (there are multiple dimensions: is it understandable, does it add maintainable code, was it tested, etc) or not?
I think "AI-friendly" says "I don't care if it's written with an AI or not: I want good quality PRs".
I would think that "slop-friendly" is the kind of projects where the maintainers don't read the code. Maybe they try the feature (maybe not even?). I think the Omarchy guy was explaining somewhere that he does not read the code anymore, he just lets his AI write Rust. This is slop-friendly IMO.
If you are not AI-friendly, it means that you refuse to accept a good PR even if you cannot tell that an AI was involved. The mere fact that an AI was involved disqualifies the PR.