We'd still need a way to know when someone violates it. When you see a copy of your licensed software being used you can at least try to enforce that, but how do you know it was fed through an AI for training?

At best that would be like a Don't Track Me flag. Some will follow it, though ironically it is also useful for fingerprinting and can signal you may be doing something worth tracking.

"Open source" doesn't really help much without the "Free and" prefix, and unfortunately there's no way to reconcile software freedom and banning specific use cases. Dunno if you remember the "can we remove Nazis from ToR" controversy awhile back but it's the same kind of thing. It's either free or it isn't.