Sorting it out on the ground always worked for me. A little walk down the cabin, a bit of "face time" with the offending article explaning the options and listing the various authorities and conditions they will have to deal with and hey presto a trouble free flight.
If it kicks off in flight take the opinion of the cabin manager, divert or continue. They are best placed to decide whether they can handle the situation and are trained to deal with it. A very supportive PA that even the average IQ challenged brit holidaymaker could understand can work wonders when the yob mentality takes over.
If you do divert make sure you have your ducks in a line coz sure as eggs is eggs the Monday morning quarterbacks back at HQ will pick over everything you have done, in slow time, in a comfy office, to see who takes the blame for the cost. Me, I don't care much about that. I am tasked with getting pax (neanderthal or not) to their destination safely and will make decisions based on that not some spreadsheet.
I have to say though that Easy are very supportive of their crews in these situations.