Is Trump or is he not in charge of the Executive Branch?
He is not a dictator and cannot simply order people rounded up willy-nilly. Barr is the veteran legal mind in the administration and is doing all that can be done within the bounds of the law...its slow and unsatisfying no doubt, but this has to been done in a manner that is above reproach. Arresting someone in a major political spectacle only to have a court dismiss the action as having been done so without sufficient grounds would be FAR worse than never arresting such a person. Make an airtight legal case against very powerful political persons across the aisle is no simple task...some seem to think the President just sits on King George's throne and commands it to be so. It doesn't, cannot, and should not work that way...though it may one day soon under future Dem single party rule.
As Barr stresses, the rule of law must be upheld...even against those of Comey, Brennan and others ilk. In the end, I believe Durham indicts some big fish...perhaps some very big fish. But if some big fish get away, you can be certain it was because there was not sufficient evidence to garner a conviction...which is different, obviously, than simply believing these people are scum and that they are guilty. Evidence is evidence...and none of us here know precisely what evidence Barr-Durham have attained.