Quite frankly I am astounded by the opinions of some captains here that think that this captain was justified in diverting the flight. Now I know it has been said that we don't know the full story, but these opinions are based on what is in this thread, so I shall do the same.
As a pax, I do not want to be incovenienced by a diversion just because the captain has a hissy fit and feels that the purser has undermined his authority. I understand that if there is a danger to the aircraft, then you dirvert, but in there situation, the only danger was the captain's hubris.
Having been in middle management with a top international firm, I have dealt with many issues with staff over the years. If you're in charge/the boss you get respect and obedience from managing your staff not bossing them. If there is an issue, you pull that person aside and deal with it or schedule an appointment with HR if it merits it. You do not start a row in front of other staff or suddenly call an event off, just because you feel that your authority has been questioned, you get through the event and deal with it after.
Now I know sales & marketing isn't the same as flying a plane and there are more immediate issues and lives at stake, but I do struggle to see that a diversion was necessary and feel that the captain could have carried on and dealt with this at destination with head office/HR if needed and put in a report. The fact that he had a tantrum and overreacted would worry me that he may be prone to making other irrational decisions if something annoyed him.