AI watermarking is adversarial, and anyone who generates a watermarked output either doesn't care, or wants the watermarked removed.

C2PA is cooperative: publishers want the signatures intact, so that the audience has trust in the publisher.

By "adversarial" and "cooperative", I mean in relation to the primary content distributor. There's an adversarial aspect to C2PA, too: bad actors want leaked keys so they can produce fake video and images with metadata attesting that they're real.

A lot of people have a large incentive to disrupt the AI watermark. Leaked C2PA keys will be a problem, but probably a minor one. C2PA is merely an additional assurance, beyond the reputation and representation of the publishing entity, of the origin of a piece of media.