Does the policy fix the issue of many low quality PRs being submitted? Unlikely. Will it fix a related but different problem? Likely.
The people who submit low quality LLM-generated PRs often don't bother to read the policies first, but at least it will be easier to reject those.
The birth of vibe coding has seen interactions on public FOSS projects increasingly reminiscent of the flame wars and moderator hammers of the old forum days. A lot of projects have been behind the curve on preparing and codifying the hammers, probably because no maintainer really wants to be a moderator, but thats where its naturally landed unfortunately.