But it is taught in class, and the reason it isn't characterised as a "coup" is because the president at the time (Coty) took the decision to call on De Gaulle

But it is taught in class, and the reason it isn't characterised as a "coup" is because the president at the time (Coty) took the decision to call on De Gaulle to take emergency powers (a decision the parliament endorsed). A new constitution was drafted and put to a referendum, before a general election. The reason it isn't talked about very much outside the communist party is because it isn't nearly as controversial as you suggest.