You're ignoring the rest of the definition I provided. I did not say it was "any takeover of power". Please read the definition I gave in full.
And I am not referring to the CEO status of Altman at all. That's not the coup part.
What I'm referring to is the fact that beyond his firing as CEO, he and the chairman were removed from their board seats, as a surprise planned and executed in secret. That's the coup. This is not a board firing a CEO who was bad at their job; this is two factions at the company where one orchestrates a total takeover of the other. That's a coup.
Again, I'm not saying whether this is good or bad. I'm just saying, this is as clear-cut of a coup as there can be. This has nothing in common with the normal firing of a CEO accomplished out in the open. This is four board members removing the other two in secret. That's a coup if there ever was one.