You are missing the fact that trumps authority over doj is plenary.
So, say Donald goes and calls out Jack and Jill from DOJ and orders them to get on those Hillary emails. Then what?
Jack and Jill go to FBI and say fork over the emails, and the FBI says no.
So Jack and Jill go to federal court and file a motion and subpoena for the judge to rule that FBI needs to fork over the Hillary emails, and the judge says no because Jack and Jill are not confirmed nor tasked as special prosecutors.
So blame it on Trump if that floats your boat. McConnell refused Trump the power to make recess appointments but I guess that doesn’t matter to you. Trump’s got your goat. Have at it.