I’m less concerned with who their boss was than I am with why the DOJ hired them and kept them around. If they were hired/kept because Barr (or Sessions, or Lynch, or Holder, etc.) thought they would be a good lackey with no conscience, then I wouldn’t want them anywhere near my firm. But if they were hired because they were capable of coming up with incisive arguments for whatever position they were assigned to defend—which is, after all, their job—then I would treat them like any other potential candidate.
A legal memo is not a statement of belief. It is not a declaration that the position defended within is right and true even when held against the most stringent demands of morality. It is a summary of one’s legal research that analyzes what the law says, the best arguments for the position one has been asked to defend, and the most pressing objections that might be raised in response to those arguments.
Lawyers get assignments that they don’t want all the time. And while they may request to be transferred to a different assignment, those requests are frequently denied. At that point, one has a professional obligation to make the best case they can. Intelligent people making opposing cases based on evidence is how the law evolves and how the legal profession advances. And following through on an argument one does not agree with can be incredibly informative, even when one remains unconvinced.