The former OLC lawyer knows how to frame the question just right:

Or, to put the question as it will present itself to lawyers in the Executive Branch: Can the President make an appointment during a 10-day break simply to overcome “political opposition in the Senate” despite the absence of any “national catastrophe,” even though it “go[es] without saying” that he cannot do so during a 9-day break? Who knows? The majority does not say, and neither does the Constitution.4