Nadella's attitude is adding mystery to mystery. It's hard to think he doesn't know the truth. Or did Sam tell him a story, nice but fake, and he believed it? That would be spectacular.
Yet Mr Nadella stands with Mr. Altman.
What if he thinks his position and company is so strong it can withstand any web of deceit Altman can weave? There is, after all, so much money to be made here it matters even on a Microsoft scale.
I think people are so tempted to contrive these multilevel conspiracy theories where Nadella and Altman are thinking many moves ahead while the board is just a slow moving group of idiots when the much simpler explanation is they are desperately trying to restore confidence. I think the main tell on this besides what was already said was Nadella making the announcement before market open- this is a guy feeling major pressure from shareholders about the strategy.
The problem with that though is that he is making impulsive decisions with imperfect information and taking major reputation risk in the process.