That wasn't his job. In fact in doing so was a break with FBI procedures.
Comey ‘Deviated’ From FBI Procedures in Clinton Probe, Watchdog Finds
Damaging the law enforcement agencies’ image of impartiality, the watchdog said
fortune.com
"we nevertheless concluded that by departing so clearly and dramatically from FBI and department norms, the decisions negatively impacted the perception of the FBI and the department as fair administrators of justice,” Inspector General Michael Horowitz said in the report’s conclusions, which were obtained Thursday by Bloomberg News.