On one hand I get their point, but on the other hand I view it as kind of pointless. Like if I go on DeviantArt forums or some other publicly viewable art repository, look at everyone's art content, and then decide to emulate their styles, that's perfectly legal and I'm not exactly breaking any ethical codes by doing so. So how is it really that much different for an AI to do the same?
Regardless, I won't be surprised when developers code in a countermeasure to defend their models against this AI malware and yet another digital arms race will be born.