Nah, I think it’s pretty clear cut. Under current US trademark law (IANAL etc), if I sound like Morgan Freeman, I’m free to do what I want, as long as I don’t try to convince people that I’m Morgan Freeman. If I’m cast in a movie because my voice sounds like Morgan Freeman, and the promo posters don’t have his name or face on them, fine. If I do voiceover for a commercial and say something like “I’m Morgan Freeman, buy Joe’s Hotdogs” then that’s already a clear violation of Morgan Freeman’s trademark, because consumers might be confused into associating Joe’s Hotdogs with Morgan Freeman.
And that’s what happened here: OpenAI “hired a machine” that sounds like ScarJo, and then attempted to associate their product with ScarJo’s brand without her permission. You’re already not allowed to do that.
And if you want to make it as a voice actor and you sound like Morgan Freeman? Try your hardest to develop a personal brand distinct from his, and don’t take gigs where people want you to impersonate him (unless it’s a really obvious parody and you’re cool with the angle).