I see it an more an inability to analyze, evaluate, and edit. A lot of "creativity" in the world of musical composition is putting together existing elements and seeing what happens. Any composer from pop to the very avant-garde, is influenced and sometimes even borrow from their predecessors (it's why copyright law is so complex in music).
It's the ability to make judgements, does this sound good/interesting, does this have value, would anyone want to listen to this, and adjust accordingly that will lead to something original and great. Humans are so good at this, we might be making edits before the notes hit the page (Brainstorming). This AI clearly wasn't. And deciding on value, seems wildly complex for modern day computers. Humans can agree on it (if you like Rock, but hate country for example).
So in the end, they are "creative" but in a monkey-typewritter situation, but who is going to sort through the billions of songs like this to find the one masterpiece?