Now as a previous poster stated the captain is in charge - that is not just a statement but requires actions. The captain of this flight clearly lost control and with not much doubt, with no knowledge to himself or the co-pilot.
So you have passengers who off their own bat, have decided to evacuate...Short of appearing at the Flight Deck door armed with a 9mm what actions do you, in your expert option, think would have restored control?
FWIW the general feeling where I work is if one of these passenger induced foul ups starts (e.g. tailpipe flames/torching at night..odd smells) and doors get opened the safest course of action is carry out the evac checklist, that way hopefully people aren’t going to kill themselves evacuating from a rolling aircraft or evacuating into/behind a turning engine.....even somebody with the leadership skills of Rommel or Patton isn’t going to stop the stampede.