For the same reason that the FBI goes after Weldon on an investigation that took place 2 yrs. ago, again two weeks before an election. Bush could never bring himself to clean house anywhere after he took office due to his "new tone" so the Clinton leftovers ran amuck.
I've been saying that for six years. Hillary packed every department within the Justice Dept. with her people, and Bush left them in. We've suffered for it relentlessly.