If your contributions are genuinely indistinguishable from AI code, then this shouldn’t affect you. There would be no way to enforce it
There is legally. Make sure they sign the DCO (Developer Certificate of Origin). They will fail at the first paragraph
(a) The contribution was created in whole or in part by me and I have the right to submit it under the open source license indicated in the file; [...]
I think they arent even trying to build an AI detector. This is more of a social signal like "dont send us an automatically generated flood of changes"