The best way to answer this is to remember what the role entails. The shift supervisor is the team leader on shift - they have to set an example for staff and customers alike in critical situations. They also have to ensure the safety and welfare of their colleagues and customers. That in mind, in this particular example it is always best to give in to whatever demands are being made. No heroics. The sooner the incident is over with the better. The smoother things go, the probability of someone getting hurt is minimised.