Earlier quoted context omitted.
Because PRs with AI need to be reviewed with a lot more scrutiny, simply because AI is good at generating code that looks good, but isn't necessarily correct. So now you're looking at a PR that at face value looks good, but doesn't reflect the author's skill and understanding of the subject. Meaning now you shift more work to the owners of the codebase, as they have to go through those verifications steps.
This makes 0 sense. It shouldn't matter if AI wrote the PR or a human.
It makes sense, because humans and AI write code different. Because humans aren't AI. The types of mistakes AI writes into code would never be done by a human.