Amazing how many people want to crucify this guy! First of all try an act like professional instructors or if you cannnot do that try just, 'nice people'.
Do we know why this man acts in this way, do we, or have we taken the touble to find out anything about this man at all. I am afraid all I have heard so far proves to me is that none of you really know how to deal with people and for flying instructors some of you should be ashamed.
Remember this man is the same as you, prick him and he will bleed, insult him and he will hurt etc etc.
Try and put yourself in his position and ask how you would like to be dealt with. Try and think how you would go home and explain to perhaps your family, your wife and children what has happened to you at work.
Most people respond to sensible sincere comments, try looking at this issue differently and you may solve the problem. Anyone can rant and rave and demand to be treated how THEY want to be treated. The skill is to get people on side so start by asking how you can help him through this problem.