If you can immediately tell "this is just AI slop" that's all the review and "attention" you need; you can close the PR and append a boilerplate message that tells the contributor what to do if they want to turn this into a productive contribution. Whether they're "good faith contributors trying to help" or not is immaterial if this is their first interaction. If they don't get the point and spam the repo again then sure, treat them as bad actors.
The thing is, the person will use their AI to respond to your boilerplate.
That means you, like John Henry, are competing against a machine at the thing that machine was designed to do.