One of the marked, but rarely noted, traits of “highly successful” people is their ability to not hold a grudge. Recent examples are the election and the voters—the forgivers and the vindicators.
Being offended, holding a grudge, “claiming your right” to object, standing up for principal—or however you want to cloak it—clinging to the past anchors oneself in the past. Of all the success skills and self-improvement steps one could learn, moving ahead without staring behind is the most worthwhile.
So, never fire someone without a recommendation letter and never argue with people not in the room.