How quickly can you depressurise an aircraft at altitude if you turn off the packs and open the outflow valve fully? As pilots with forced air breathing gear, wouldn’t anyone else without forced air (even with an oxygen mask) pass out fairly quickly after depressurisation so long as you maintain altitude, possibly buying you some time?
I guess it could kill some people in the aircraft, however I assume that is preferable to the aircraft being used as a weapon.