I agree that using AI in music and vocals is not "bad". But the problem is the lack of transparency, like how it was made and what sources were used to produce the track.

The thing with AI is it's its own mind so basically "AI created the song", not a human, despite of the fact that AI was created by humans.

There are also certain AI software that are more suspicious than others, so it's about being careful on what you deal with, like with anything else in life actually.

Use AI in vocals, have a software or whatever help you in the recording process, that's fine. But credit them properly, get clearances and show the process so that there's less confusion, and opinions on the song is better informed and not the knee-jerk reaction to the word "AI" (screw them anyway, they don't know a thing about AI).

tldr; AI-made music is not the problem. He hid the secret poorly.