It's not. The author is summarizing things that don't seem to make sense based on current info - i.e. the author wasn't surprised, but is wondering why Altman was.
There isn't anything, as far as I can tell, structure specific that caused this ousting. If it was a normal for-profit structure with a board of directors this same event could have played out.
What is surprising to Sam, and any casual observer, is this looks to be a massive overstepping of the board. By all accounts it looks like Sam was excelling in his role, and to fire him for seemingly no reason with no real transition plan is incompetence and should be unexpected from any serious company.
> Sam Altman says he wants to develop AI for the benefit of humanity yet at the first possible moment he sets up a deal that sells 49% of their endeavor to Microsoft.
Maybe Altman thought Microsoft would be the best way to fund the venture, while still benefiting humanity. It's not as if selling 49% to Microsoft will guarantee the venture won't succeed. Altman isn't omniscient; he's making his best possible moves based on his prediction of future, as we all do.
I'm sure Altman wsn't surprised.