The de-escalation skills amongst our new generation of cabin crew are frightening. I've witnessed it myself a handful of times. Absolutely spot on to say that after a while, it becomes a face saving exercise and logic totally goes through the window. Race and a natural subconscious fear of those who look different most likely played a part here too. Disembarking everyone is proof of this. A drunken or otherwise physical bust up onboard wouldn't have even illicited that reaction.