Good people sometimes "Lose it" because they are frustrated, not feeling good, or simply just having a bad day. It has happened to me and almost everyone I know . . . and when it does, most of us immediately regain control, apologize, and move on in our lives doing the best job we can being respectful and kind. Stuff Happens!
Some people, when they don't get what they want feel they can intimidate and threaten harm to individuals to get their perceived obstruction to disengage. When a group of individuals that are party to these kind of behaviors do not intercede and demand an end to this behavior, the aggressive intimidating individual feels a license to continue a bad disruptive approach to achieve their way.
It is not an acceptable approach to sit back and watch someone bully or intimidate individuals at anytime. We must always stand up and reject this behavior in a loud and clear manner. If an individual can't help themselves, refuses to get help from at a professional level, then we must separate ourselves from this assault. If the group in which bullying occurs demonstrate strongly that this behavior will only produce negative response from the group, then the bully will most likely withdraw.
There are times to sit back and wait things out to not cause a scene. It is my opinion that we should stand up to aggressive intimidation immediately and never allow these events to occur in any group where we are participants.