What I DO know is that Rosenstein was appointed by President Trump long after everything related to the Uranium One case took place. He hasn't been fired yet, and if he does get fired it will surely be for a damn good reason.
That would result in both Mueller and Rosenstein having to resign in order to tend to that matter, and therefore remove most indications of bias and conflicts of interest in the investigation of Trump.
Baring that, Rosenstein and Mueller should not be allowed to continue unchecked.