"If these new emails prove nothing but the fact that the investigation has been reopened ushers in a Trump presidency, how will Comey feel then?"

Uh, like he did the job that was entrusted to him?  That is -- law enforcement, and not culture warfare.

Really, must everything be a zero-sum in this election?   Forget enforcing law and order, all that matters is that Hillary must be elected? (I swear, the zero sum thinking of the leftish Catholics just as lame as that of the trads, who vote only for the abortion issue and nothing else).

You must understand, MSW, that the job of law enforcement is often based on investigating likelihood of wrong doing.  

The emails  in question from the Weiner laptop are not the same emails that the Clinton IT team worked over -- no, these emails are unscrubbed, unvetted, unexpurgated.   Comey knows this, and likely has seen evidence in the 650,000 he found disturbing enough to warrant this further investigation.