His voice doesn't sound that distinctive to me. He's going to have a hard time unless he can find some emails that say, use David Green's voice.
He'll likely file in California or Federal and ask for Jury trial. I think a Jury will be sympathetic. I doubt Google will want this to go to a jury trial - not worth the risk, further news cycles of negative PR and impact on staff morale. NPR is credible and liked.
His voice doesn't sound that distinctive to me.
It doesn't matter whether it sounds distinctive to you. What matters is whether it's close enough to the real person's voice to be an infringement.
Just like it doesn't matter if you used a machine to duplicate a painting. It's still an infringement.
You can't publish a Harry Potter novel and then throw up your hands and say, "It wasn't me. The AI decided to name the characters Hargid and Hermione and Snape."
Google says it paid a voice actor. If it provides proof of that, good. But like with a lot of AI things, we're in new territory here.
Seems like there's a market for a tool that can compare an AI voice to a library of known famous voices so that companies like Google can tweak their machines to not sound too much like someone who can be harmed by a sound-alike.
I think a lot of sport announcers sound the same. There might just be classes of voices where you expect a faceless voice in some scenario to sound a certain way.