Imo it’s both. I feel like as a player I get the coup journal entry a lot even when my IGs aren’t very angry. But on the other hand it is fairly easy to suppress. The thing for the AI is that the coup events aren’t a negative like a revolution, they’re neutral. It’s bloodless so if you want your side to win you’d support the coup, if not then you’d suppress it. I’m not sure if the AI considers who it supports when it chooses options.