Its unlikely that this did not use his work, these models require input data. Even if they took similar art, that would only resolve the issue of Greg himself but would shift it to those other artists. Unless there is some sort of unspoken artistic genealogical purity that prevents artists with similar or inspired styles from having equal claim on their own creations when inspired by another.

It also could be outputs generated from another AI model. But I don't think people who see ethical problems in this care about the number of steps removed and processing that occurs when the origin is his artwork and it ultimately outputs the same or similar style. The result is what bothers people, no matter how disparate or disconnected the source's influence is. If the models had simply found the Greg Rutkowski latent space through random chance people would still take issue with it.

The ability and willingness to generate images in a style associated with a person, without consent, is a threat to that persons job security and shows a lack of value for them as a human. As if their creative expression is worth nothing but as a commodity to be consumed.

The people supporting this don't care though. They want to consume this person's style in far greater quantities and variations then a human is capable or willing to fulfill. That's why these debates are so fierce, the two sides have incentives that are in direct conflict with one another.

We currently lack the economic ingenuity or willingness to create a system that will satisfy both parties. The barrier of entry to AI is low, someone at home has every incentive to maintain the status quo or even actively rail against artists. Artists will need a heavy handed approach from the government or as a collective to combat this effectively.

If it's inspired then at that point I guess it might not be copyright infringing unless it's an accurate enough recreation of a copyrighted piece... And it looks like my mind filled in the gaps to assume it was copyrighted work being used.