It's really about keeping control. Some leaders might shout, curse, and intimidate to make a point and get peoples attention, but if they're good, they know exactly what they're doing and they're in total control of their actions. They can change course as the situation dictates.
Getting into physical altercations, choking, grabbing people shows that you have lost control. Cursing and throwing a vase when interacting with a 64 year old secretary shows that you have lost control. People who can not control themselves should never be put in leadership positions.