You just hit on the overall problem.
FBI Comey was scared to death to go after hillary since he knew if he went after her in essence he was going after a huge portion of the govt..that was actually in on the Clinton Foundation corruption. There was no chance that lyin loretta would prosecute so he had little choice.
So he probably did the best he could by giving a later administration all the goods he had on her and then said don't prosecute. Weird but understandable.
Give me a break. Comey’s a Clinton stooge.