I don't fully understand how this works, but if they've created a way to replicate his style that doesn't involve using his art in the model, how is it problematic? I understand not wanting models to be trained using his art, but he doesn't have exclusive rights to the art style, and if someone else can replicate it, what's the problem?
This is an honest question, I don't know enough about this topic to make a case for either side.