> it could have been rewritten, rewriting PRs is cheap today, but that isn't the question. the question is, would it have been accepted had it met all the quality and engineering standards and full disclosure that it was 90%+ LLM generated?

In this case it looks like the answer is "Yes"; the PR was not dismissed immediately, it was first examined in great detail!

Why would the maintainer expend effort on something that was going to be rejected anyway?