Broadly speaking, GPL is a license that has specific provisions about creating derivative software from the licensed work, and just saying "fair use" doesn't exempt you from those provisions. More specifically, an advertised use case (in fact, arguably the main one at this stage) of the most popular closed models as they're currently being used is to produce code, some of which is going to be GPL licensed. As such, the code used is part of the functionality of the program. The fact that this program was produced from the source code used by a machine learning algorithm rather than some other method doesn't change this fundamental fact.

The current supreme court may think that machine learning is some sort of magic exception, but they also seem to believe whatever oligarchs will bribe them to believe. Again, I doubt the law will be enforced as written, but that has more to do with corruption than any meaningful legal theory. Arguments against this claim seem to ignore that courts have already ruled these systems to not have intellectual property rights of their own, and the argument for fair use seems to rely pretty heavily on some handwavey anthropomorphization of the models.