The number and size of AI-assisted PRs have reached a tipping point. Reviewing them already consumes a significant amount of time, and even filtering out the obvious ones is a drag. More importantly, the risk/reward balance is shifting in the wrong direction. For now, placing constraints on AI-assisted contributions feels like a sensible way to manage that risk.
Will this policy reject or slowdown otherwise beneficial PRs? Potentially. But that is the tradeoff. Until there is a better way to offset risk, this one is probably the least bad strategy.