I think if only submissions that follow a certain guideline are accepted then I doubt this will result in lower quality, it will even likely increase its quality by fixing relevant bugs. So I don't think quality will degrade so long as parts of it don't turn into 100% automated code factories.
The only thing that remains are the ethical challanges but hardly anything in this world is completely free of entanglement to ethically questionable practices. You use a lenovo to write code? They are probably funding millions into AI. You have a nvidia gpu in your computer? Yeah, ofcourse it is good to take a principled stand against corpo-fascism. But holier-than-thou approaches will only bite back.
But I don't understand why people did not vote for accepting AI code but with disclosure. Seems like there is nothing to lose there even if you are an AI supporter. And could be useful for statistical purposes like analysing how human vs robot PR differ in things like rejection rate/severity of bugs found etc