In a blow to the prosecution, jurors at the arson trial of former Scranton firefighter Thomas S. Gervasi will not hear any reference to 36 insurance claims Mr. Gervasi filed over the years before he allegedly torched a building in 2008 that destroyed a garage and displaced 14 people in an East Scranton apartment building he owned. The Superior Court ruling, contained in a nine-page memorandum filed Monday, was based on an appeal filed in December by the Lackawanna County district attorney’s office on the eve of Mr. Gervasi’s trial.