> Given that no version of the GPL (or other OSI license) has provisions about that type of usage, they are all AI-friendly.

With copyright laws, not explicitly granted means forbidden, unless covered/overridden by law (like fair use for instance). So this could be an argument against AI use without attribution / copyleft, since it's not explicitly granted.

Now, it remains to be seen if law / jurisprudence deems AI use exempt from copyright restrictions (or something like fair use applies).