It seems unlikely that a law intended to prevent AI from impersonating existing human artists would prevent a human artist from doing anything other than using

It seems unlikely that a law intended to prevent AI from impersonating existing human artists would prevent a human artist from doing anything other than using AI to impersonate another human artist. However other laws related to copyright infringement might still apply, given that in context, "sounding a lot like a previous AI artist" means "sounding indistinguishable from an existing human artist."