The performer is one of many who are responsible for crowd safety. Critically, they not only have a direct line to the crowd, they have a massive influence on the crowds behaviour, probably greater than anyone else at the event. He could’ve chosen to help diffuse the situation, but instead decided to ramp things up. This makes him culpable and in part responsible for the deaths.
A mass casualty event was declared at 9.38pm and this cockroach continues his set for another 40 minutes. There is no way the declaration of a mass casualty event didn’t make it through his ear piece. He knew exactly what was going on and along with his entire team, made the choice to continue. While there were failings from the top down, he is definitely part of the decision making process that decided to carry on. If the decision to stop earlier had been taken there is little doubt further deaths could’ve been avoided. He is culpable. He is responsible.