The conclusion of this would be that you can never license AI generated code since you can't get a release from the original authors.

Of course in practice it would work exactly in the opposite fashion and AI generated code would be immune even if it copied code verbatim.

I don't see what's wrong with that personally. If I pirated someone's software, and then sold it as my own and got caught, just because I sold a bunch of it doesn't mean those people who bought it now are in the clear. They are still using bootleg software in their business.