It's illegal to use someone's likeness without their knowledge in a lot of places.
Like I'm sure that some relative of Elvis Presley was paid for the Elvis movie that was recently released, but is anyone going to get paid for those new Napoleon movie/miniseries?
At some point things enter the public domain, and facts aren't copyrightable.
It's illegal to use their likeness claiming that it is actually them. I fail to see how AI voices are legally any different at all than using a human impersonator.