I'm not a lawyer, but doesn't there have to actually be a reasonable voice resemblance to conclude that there's impersonation? In a side-by-side "taste test" I don't think these two voices are very similar.
No, they can't legally use an adult white female's voice that might be mistaken for Johansson's in their product and imply it has anything to do with Johansson's performance in the movie _Her_.
So... Smart tweet there, Sam. Really smart.
(I don't quite get why the Techbro - venture capitalist sphere is so enamored with this guy. From all I've seen reported about him, he seems not only a grade-A arsehole, but dumb as a fucking brick. But maybe they identify with that.)