If the model produces content that would be a copyright violation in any other context, it doesn't stop being a copyright violation regardless of any of these decisions. No one has ever disagreed with that; it's the functional abolition of copyright and if you're okay with that, then you're not arguing for this stuff, you're arguing for the abolition of copyright.
The argument is that if you trained the model with copyrighted data, and then you or someone else separately used the model to generate novel media which was not legally similar enough to any copyrighted work to make it a copyright violation, that that isn't violating copyright, it's fair use. Basically, using it to make your own original content is legal, and using it to create an unauthorised reproduction of a copyrighted work is illegal. Just like all other software.
The argument is that if you trained the model with copyrighted data, and then you or someone else separately used the model to generate novel media which was not legally similar enough to any copyrighted work to make it a copyright violation, that that isn't violating copyright, it's fair use. Basically, using it to make your own original content is legal, and using it to create an unauthorised reproduction of a copyrighted work is illegal. Just like all other software.