Whether the license is revokable or not is irrelevant when the action isn't permitted by the license anyway.

In particular, the primary purpose of AI as we know it is to strip off attribution, which is explicitly forbidden by basically every license in existence.

True, license is probably irrelevant here because they aren't even intending to comply with the terms of it.

To nitpick "explicitly forbidden" isn't quite right. Licenses basically only grant more permissions, they can't remove them. It's explicitly excluded from the rights granted by the license, but it's not explicitly forbidden because it is the law that might or might not forbid the activity, not the license.