I don't think anyone is debating whether taking a photo during a serious meeting is a good idea
It's wrong to unnecessarily fire someone in front of their colleagues. It destroys morale and it's essentially a form of public humiliation. A better response would have been to ask to put the camera away and remind people it's a serious meeting.
If I was a CEO trying to get the house in order and at that very second Instagram is more important to you... you're gonna have a bad time.