Laura Ahearn, a leading children's advocate tapped by Bishop William Murphy to help the Rockville Centre diocese clean up its sex abuse scandal, called the bishop's effort phony and said she will no longer work with the diocese.  Ahearn called on Murphy to resign and lambasted him for failing to pay restitution to 45 alleged victims of sexual abuse by priests on Long Island while waving a sign that declared The CEO Must Go! and marching alongside 15 other protesters outside St. Agnes Cathedral yesterday.  Ahearn is the executive director of Parents for Megan's Law.  She charged that Murphy is more concerned with PR spin than protecting children.  She said he told her that when he was second-in-command in the Archdiocese of Boston he had no legal obligation to call police when cases of alleged sex abuse crossed his desk.  Ahearn said, That demonstrated that this is a person that is incapable of putting children's safety as a priority over preventing scandal and protecting child molesters, adding, We won't be part of his PR spin.