Most importantly, McGahn has shared his observations and documents with Mueller. (We also know that McGahn preserved documents that may be critical to the special counsel’s investigation.) For this alone — the ability to gather information and relay it to the special counsel — it was a good thing he stayed. He also recused himself and the entire White House counsel’s office from the Mueller investigation, thereby protecting himself and his subordinates, no doubt, from being put in the position to do unethical or possibly illegal things. For that, his subordinates owe him a debt of gratitude.
McGahn did more than that, however. He blocked the firing of critical figures. (Did he also convince Trump that, for some reason, Trump himself couldn’t/shouldn’t fire people directly? If so, he gets extra points.) Without McGahn in place, Trump may well have already fired Attorney General Jeff Sessions, Deputy Attorney General Rod J. Rosenstein and Mueller. McGahn reportedly threatened to resign if the president canned Mueller.
One could easily see a new White House counsel trying to “un-recuse” himself and to readily carry out Trump’s wishes — whether it is firing important figures or conducting pardon discussions with convicted felons such as Paul Manafort, in an effort to deprive Mueller of information essential to his investigation.
While we can deplore McGahn’s participation in some of the executive orders Trump has issued — most clearly the Muslim travel ban — we can imagine the executive orders and loony, unconstitutional schemes that would have emanated from this White House without him.
Whatever you think of McGahn’s judgment in remaining on the job and whatever you think of his role in selecting judges, you can be certain his replacement will be worse. Trump now feels under siege and wants only yes men around him. There is a great likelihood that McGahn’s successor will be willing to facilitate a reckless president’s desires rather than block them. Once more, it would be nice if Republicans had the gumption to pass legislation protecting Mueller, and to warn that impeachment hearings would commence if Mueller, Sessions or Rosenstein are fired.