I don't think the controversy stems from any provisions in the equity plan and grant documents. The Vox article only talked about the off-boarding NDA, and that's all that Altman is talking about here:
> there was a provision about potential equity cancellation in our previous exit docs; although we never clawed anything back, it should never have been something we had in any documents or communication.
Mind you, Altman could still be lying and that would be very much in character, but this also sounds like a very plausible explanation for the hubbub.