That would imply they hadn't considered that Altman was beloved by vital and devoted employees? That big investors would be livid and take action? That the world would be shocked by a successful CEO being unceremoniously sacked during unprecedented success, with (unsubstantiated) allegations of wrongdoing, and leap on the story. Generally those are the kinds of things that would have come up on a "Fire Sam Pro and Cons" list. Or any kind 'what's the best way to get what we want and avoid disaster." They made the way it was done the story, and if they had a good reason, it's been obscured and they've been mum.