I don't agree with the premise.  From the outset, it was apparent that Mueller was out to get Trump.  In addition to his very blatant conflict of interest re: his relationship with Comey (read the guidelines for becoming a Special Counsel), look at the political affiliations of his personally chosen staff.  Several actually worked with Clinton, most contributed to her campaign, and one was Hillary's personal lawyer in a matter.  Not a Conservative in the bunch.  In choosing his staff,  he stuck his finger in the face of POTUS Trump and his supporters.  Now it comes out, as reported even in such mainstream media outlets as Newsweek, that Mueller and Rosenstien were willfully complicit in the covering up of illegal activity- bribes and kickbacks- in the Uranium One deal- hid it from Congress.  He is dirty.  Any Attorney General other than Jeff Sessions would have commissioned a Special Prosecutor/Counsel before now regarding these matters.  Hopefully, a real AG will be on the scene soon.