I'm allowed to hear a copyrighted tune, and even whistle it later for my own enjoyment, but I can't perform it for others without license.
People need to stop anthropomorphizing neural networks. It's a software and a software is a tool and a tool is used by a human.
It's interesting how polarizing the comparison of human and machine learning can be.
What makes far more sense is saying that someone, a human being, took copyrighted data and fed it into a program that produces variations of the data it was fed. This is no different from a photoshop filter, and nobody would ever need to argue in court that a photoshop filter is not a human being.