Your Op's manual says a minimum of 5 cabin crew required for a flight where as the legislation says 4 is the minimum. One of your crew doesn't report for work, do you load the passengers and go anyway?
Your pax load is less than 50%, are you allowed to make a judgement call and load and go? It would appear, after this case at Queenstown has played itself out, the answer would be no. The man in the Court House knows best.