Doesn't sound to me as if the flight was in any physical danger, or likely to be so. Diverting the flight if there are unruly passengers causing a physical threat is one thing - and rare. Insisting on diverting because of a personal issue with cabin staff, where the main threat is to the paperwork...seems a ridiculous overreaction. This is not the behaviour of a rational captain in sober command of his senses; it's Basil Fawlty attacking his car with a tree.