It doesn't really matter: the AI model is a compressed representation of copyrighted works processed by a generic, non-artistic algorithm specifically engineered to extract the artistic features of such works.

Conceptually, it's very similar to running lossy JPEG over a single copyrighted work versus a giant folder of works from different artists, then shipping that compressed collection to you customers so they cut and paste sections of those works in their collages. The output your customers create with this tool might be sufficiently original to warant copyright protection and fair use, but your algorithmic distribution of the original works (the model) is a clear copyright violation, it doesn't matter if it affects a single artist or thousands.