It sounds like a moral stance on its face, but honestly they probably wouldn't care if someone posted a reasonable amount of AI-generated music that was high quality enough to gain a following of listeners.

This is likely a stance to prevent an individual from producing thousands of AI generated tracks and attempting to flood the zone for anyone browsing and searching.

There's a lot of music on Spotify for example that tries to latch on to current trends in an attempt to get pulled into search results and recommendations.