Never negotiated on exit.
Why? OpenAI is a shitshow. Their legal structure is a mess. Yanking vested equity on the basis of a post-purchase agreement signed under duress sounds closer to securities fraud than anything thought out.
OpenAI doesn't have shares per se, since they're not a corporation but some newfangled chimeric entity. Given the man who signed the documents allegedly didn't read them, I'm not sure why one would believe everything else is buttoned up.