Let's suppose all that stuff is absolutely true, that when Sam Altman was a 13 year old kid he assaulted his 4 year old sister, that she's troubled because of it, and he made some attempts to buy her off, perhaps money in exchange for silence. Why would the board decide to suddenly fire him because of that, after all this time? He was a minor who would not understand the consequences.
No, I'm confident that it has nothing to do with that. It must have to do with the current business. Maybe there's a financial conflict of interest. Maybe he's been hiding the severity of losses from the board. Maybe something else. But you don't fire a CEO because you discover that he committed a crime at age 13.