He's arguing law in a technically-oriented fashion, and thereby pointing out that if you can find even one example of a way that a song could generate revenue f

He's arguing law in a technically-oriented fashion, and thereby pointing out that if you can find even one example of a way that a song could generate revenue forever, then the song "itself" is infinitely valuable (which is also sketchy, economically, as mentioned elsewhere). All of this argument is ultimately pointless, of course, as corner cases do not invalidate laws, and the real root problem with everything related to such things is the confusion between sets and members of sets: they're both called "the song".