This is very fascinating, I love thinking about this stuff, as it really gets into the elements of what art and music really are defined as. To my very noob knowledge of this stuff, I believe this can just be thought of as another tool in the arsenal or word in the vocabulary of composition. I find this not actually too different than free improvised music, as a system of humans are making collective choices on the total outcome based upon feedback. To me it doesn’t matter if a machine is doing it or humans, in order for it to be called ‘music’. Also, unless the machines continue to play on infinitely, there has a be another human ‘artistic’ force that decides to end the piece, and then decide what goes onto the media of listening for other humans. This by nature I believe automatically makes it a human choice of ‘art’ or ‘music’ as its released into the world. IMO it also doesn’t matter at what point the creation starts, take for example DuChamp, who by just deciding an object is ‘art’, makes it art.
I personally have not vested too much time or energy into learning about AI, so I’m coming at this from a purely human standpoint.