Lots of different instructions around about FD crew getting involved in passenger disputes, not sure what the Ryan Air policy is. The idea is to avoid the possibility of any physical contact between disruptive pax, (who may be on Ice), and crew, whose job it is to fly the aircraft. In this instance I would have expected the cabin manager to report to the Captain who, in turn, would call the ground handling agent and ask for police to the aircraft immediately, to remove a disruptive pax. When the police are on board and the disruptive pax is restrained then, by all means, go back, thank the police and apologise to the ladies involved in this unfortunate incident. Charging into the fray like Batman only to get injured to the point you can't operate is not a desired outcome!