If an author of a PR just generated code with an LLM, the GitHub PR becomes an incredibly inefficient interface between a repository owner and the LLM. A much better use of the owner time would be to interact with LLM directly instead of responding to LLM generated PR, waiting for updates, responding again, etc.

As a project maintainer, I don't want to interact with someone's LLM. If a person submits a PR, using LLM or not, the person is responsible for any problems with it. How they respond to review is a good indicator if they actually understand the code. And if they used a bot to submit the PR, I'd simply consider it a spam.

Yep, the indirection through the PR author is almost always inefficient and error-prone unless the author is really knowledgable about the code (many aren't).