If OpenAI commissioned a voice actor to lend their voice to the Sky model, and cast on the basis of trying to get someone who is similar sounding to the Scarlett Johannson, but then did not advertise or otherwise use the voice model created to claim it was Scarlett Johannson - then they're completely in the clear.

Because then the actual case would be fairly bizarre: an entirely separate person, selling the rights to their own likeness as they are entitled to do, is being prohibited from doing that by the courts because they sound too much like an already famous person.

EDIT: Also up front I'm not sure you can entirely discuss timelines for changing out technology here. We have voice cloning systems that can do it with as little as 15 seconds of audio. So having a demo reel of what they wanted to do that they could've used on a few days notice isn't unrealistic - and training a model and not using it or releasing it also isn't illegal.