> Training a model on a bunch of images by {artist}, and then telling it "Generate me 20 images in the style of {artist}" seems pretty close to this ruling.

Maybe, but that is not how dalle and other generative AI work right now it is trained on a huge number artists and images. Not just mixing and matching from images from one artist even if you ask for something in one artists style. Generated an images that falls under copyright seems possible, but automatic.