A gang of ghoulish bullies broke into a bizarre Halloween dance in front of a television director on his way to work, then pummeled the senior when he tried to walk around them, police said. John Sullivan, 72, had just gotten off the train at Sixth Ave. near W. 43rd St. about 2:20 a.m. Monday and was heading to 30 Rockefeller Center when nine people in their early 20s suddenly blocked his path. “They were circling around me, and they were pointing their fingers in my face. They’re dancing, and all of a sudden they’re punching me. They beat the...