It wasn't the dancing that bothered me, it was the shooter. Incredibly random and did not make any sense. Surely the writers could have come up with something not so out of left field for the five to need to use their new knowledge. And the fact that the shooter looked practically like that Dylan kid and the Sandy Hook shooter really did not sit well with me. I guess because those shootings really affected me. I don't know. Maybe I'm looking too much into it but I was really disappointed in the "catastrophe" being that shooting.
You are definitely not looking too much into it, it's a warranted feeling! I agree that the shooting scene should have been omitted. It was unnecessary, very random and distasteful.