Its suspicious that the Washington Post didnt also refer to the related Clause 3 of the referenced Section. Heres Clause 2 & 3 of Section 2 of Article II:
Clause 2: He shall have Power, by and with the Advice and Consent of the Senate, to make Treaties, provided two thirds of the Senators present concur; and he shall nominate, and by and with the Advice and Consent of the Senate, shall appoint Ambassadors, other public Ministers and Consuls, Judges of the supreme Court, and all other Officers of the United States, whose Appointments are not herein otherwise provided for, and which shall be established by Law: but the Congress may by Law vest the Appointment of such inferior Officers, as they think proper, in the President alone, in the Courts of Law, or in the Heads of Departments.Clause 3: The President shall have Power to fill up all Vacancies that may happen during the Recess of the Senate, by granting Commissions which shall expire at the End of the next Senate session.
What Im seeing with Clause 3 is that a justice appointed to fill a vacancy during a Senate Recess does not have the job until they decide to retire, the job actually expiring at the end of the next Session.
Also, the Constitution doesnt define what a session is. But historical records show that a session can be as short as a day. So even if Obama appoints Garland during a Senate recess, the Senate evidently only needs to change its schedule a little to restart the justice nomination and consent process.
"The narrower question, starkly presented by the Garland nomination, is what to make of things when the Senate simply fails to perform its constitutional duty."
Also, regarding the argument that the Senate fails to perform its constitutional duty to give or withhold its consent, historically there are several examples when it took more than a year for a vacancy on the Supreme Court to be filled.
Long Supreme Court vacancies used to be more common
So what am I overlooking?
Congress can always change the number of justices--so in theory if they were to reduce the total to 8 there would be nothing Obama could do about it. (I'm not sure if he would have a chance to veto a change--of course a veto can be overridden--or if he has no say at all.)