 The clerks and custodians soon followed.When the university settled with the AAUP, the vast majority of professors went back to work teaching, but Levin, Zinn, Piven and two others refused to cross the other unions' picket lines.Levin and Zinn were two of the harshest critics of Silber's top-down "industrial" paradigm of university administration, in which Silber equated an institution of higher learning to a car factory.