I have no clue about all these copyright litigations and most make no sense to me anyway, but when you put it that way, yeah, that sounds like a weak claim. Again, no idea if a court would see it that way, but if you take it a step further you can almost claim that software is not GPL-3 compliant, because it's being developed using non open-source IDE. Oh, we cannot prove it? But then, we also cannot prove these NN weights are not crafted by hand, I guess.