Hmm, I wouldn't summarize it that way on first read, but I can understand and perhaps agree with the interpretation.
How I read it, the second comment is saying that AI music competes with machine-replicable human music, a subset of human music, but not all.
Frankly, while Brian Eno's Music for Airports was monumental in the history of ambient music, in 2024 people unfamiliar with it aren't going to be able to tell it apart from select AI clips (as much as that will hurt to admit). That's less about it being generic and more about how good AIgen can mimic humans. Just like how humans couldn't tell apart human from AIgen in impressionist art: https://www.astralcodexten.com/p/how-did-you-do-on-the-ai-ar... -- we wouldn't use that example to say that human art is just generic slop.
On re-read, I do think the thread started off on the wrong foot by using the word generic. Ambient music is simply some of the easiest music to machine generate being minimalist with heavy use of synthesizers, and much of it was machine generated in the first place in a DAW.
Fair. Your characterization of AI music is a bit ambitious. AI still can't write a breathtaking short story or poem: it can write a mediocre one of standard themes indistinguishable from a student, but that's it. I would argue that AI images is a special case: a photograph is after all not truly "art".