A federal judge gave a rabbi the go-ahead to pursue a claim that Cozen O’Connor P.C. helped a synagogue client cheat him out of half his deferred compensation.In a written opinion last week, U.S. District Judge John Z. Lee declined to dismiss a count of aiding and abetting fraud that Rabbi Stanley Kroll included in his lawsuit against the firm.Kroll alleges Cozen worked with Chicago Loop Synagogue — the congregation he led for almost 40 years — to drastically reduce the amount of money he would receive …