I won't merge anything AI generated in any of my FOSS projects, unless I'm successfully deceived.

In the first place, I do not regard a copyright notice and license on AI generated code to be valid in my eyes, so on those grounds alone, I cannot use it any more than I could merge a piece of proprietary, leaked source code.

The copyright office agreed with you about the non-copyrightability of AI generated media so in that sense you can safely ignore copyright claims on anything AI-generated.