The board was Altmans boss - this is pretty much their only job. Altman knew this and most likely ignored any questions or concerns of theirs thinking he is the unfireable superstar
Imagine if your boss fired you - and your response was - I’ll come back if you quit! Yeah, no. People might confuse status with those of actual ceo shareholders like zuck, bezos, or musk. But Altman is just another employee
The shareholders can fire the board, but that’s not what he’s asking for. And so far we haven’t heard anything about them getting fired. So mostly this just seems like an egomaniac employee who thinks he is the company (while appropriating the work of some really really smart data scientists)
What evidence were you expecting to find? The board said that Sam wasn't candid with his communication. I've yet to see any evidence that he was candid. Unless the communication has been recorded, and somehow leaks, there won't be any evidence that we can see.