My understanding is that the legal protections for the board of directors can quickly evaporate if they know about such lies and do not take actions. This is a major point of contention in the Oxford LLC bankruptcy proceedings per my understanding after the founder was found to have been persuing several kinds of fraud.
After they caught him in a lie, they may not have been able to not fire him.
I wonder if it's an elaborate dance.
They can't legally not fire him. But they can legally re-hire him after firing him. So ironically the ONLY way he can continue at nVidia is by being fired - we just have to wait a few days and there will be an Altman-like resurrection.