"Passing similarity"? All her friends and coworkers say it sounds like her - she describes being contacted by friends who thought she'd done it. A lot of the public, including HNers, identified the voice as hers, independently - not in some A/B test, but they heard it and said to themselves "Johanasson did the voice for this."
You're the only person in the room who thinks OpenAI didn't use samples of her voice for their voice model - or that the voice has "passing similarity."
Altman approached her asking her to do it. She refused; they went ahead and did it anyway, probably using interviews since the audio would be very clean - and two days before they went live with it, Altman tried to negotiate a second time and was rebuffed. Released it anyway.
Why would Altman feel the need to panic-negotiate a second time, days before they went live, if they hadn't used her voice for it?
If OpenAI designed it to sound like her, that's Midler tort. They actually used her voice to train it, which means Midler tort and more. The question will be how much more - I hope they get sued into the ground.