Go here to read the story. One aspect of the Pope’s well known vindictiveness, is that people who run afoul of him know they have nothing to lose by trying to damage him. If you are perceived as an enemy by Pope Francis, there is no hope of him forgiving or forgetting.
Fr Ganswein isn’t being vindictive or score settling. He is publishing his honest experience as Pope Benedict’s secretary. I’m sorry for him that the truth has gotten him in trouble with his superiors.