Supposing one wrote the whole piece by hand and then used one "AI" plugin in the final mastering chain. A nightmare awaits.
I think you're mixing apples and oranges.
The question that was before the court was whether an "original work" created a non-human process could be given a copyright. Whether or not the underlying algorithm was AI didn't have any part of the legal question.
The court made a ruling strictly on a matter of law - copyright is only conferred to works created by a human.
I was meaning more along the lines of a previous statement which said that PROs may insist on knowing if AI was used in any part of the song. "Created" is also nebulous unless it means in entirety, in which case, that's another can of worms.
Does the fact that a human "created" the prompt, count? Or, are we saying that the "machine" decides one day to write a song unsolicited and send it to me?
Wooly as heck and not heard the last of it.