> How will they know if an LLM wrote the code?

The problem isn't just the code - the documentation for the change explaining what it fixes, how, why, what testing has been done, and so forth is often either lacking, far to verbose, or both (massively verbose without actually containing much useful information or other sense).

You raise a valid point for the future: when the average quality of submissions is good enough that it is impossible to tell the difference between human (or human aided by AI but giving its output sufficient review/rewrite) and LLM/agent submissions, then the issue will have gone away. But, given the problems projects like this are seeing it is obvious that the technology (or the people using it, probably both) are not nearly there yet.

> The best LLM policy…

That is a great policy. If only the entire world would follow it, or in fact even ever read it.

If the only reliable way for now to not be suffocated under a mass of bad AI submissions is to refuse anything that even vaguely sniffs of AI, then that is what many projects are going to have to do. If that offends you, then fork the project and patch your changes in, or vide code one from scratch yourself, then you can keep maintaining that along with all the submissions you get for fixes. Let time tell which the right decision is :-)