Suno might, but apparently the contract is just with some person who is using Suno to help create this, not Suno itself. So what incentive does Suno have to keep the voice? They didn't sign the 3 million dollar contract. They're not getting any money out of this deal.
Edit: though there's probably not a deal at all, so there's that.
Give it a year or so and they'll both pretend that this never happened.