Thanks for posting this nice analysis of Constitutional law. I would guess that Professor Yoo's analysis may be in error in two places.
Consider: (underlining mine)
Mr. Pence has tested negative for the coronavirus. But suppose that changes and both he and Mr. Trump are too sick to perform the presidency’s duties. Article II of the Constitution states that in “the case of removal, death, resignation or inability” of both the president and vice president, Congress has the authority to declare “what officer shall then act as president” until the disability ends or a new president is elected. The term “officer” poses a problem for the current law.
The "current Law" referred to here is is both Statutory (The Succession Act of 1947) and Constitutional (Amendment XX). Both of these laws post date Article II. And certainly Amendment XX would trump Article II. Thus the argument over how "officer" in Article II is to be interpreted in a post Twentieth Amendment America, in the instance of succession to the Presidency, would seem to have been unequivocally settled by these later laws, and in particular by Amendment XX.
Consider also:
Further, the Incompatibility Clause of Article I provides that “no person holding any office under the United States, shall be a member of either house during his continuance in office.” That implies that neither Mrs. Pelosi nor Mr. Grassley could become acting president without resigning from Congress, which would remove them from the statutory line of succession.
I'm quite sure Mr. Loo is already regretting having written this. He knows this situation arises regularly in law and is handled by coincident acts. Resignation from one post and accedence to another are treated as coincident, simultaneous acts; not successive acts. Example: A Vice President can not also be President. If the President dies, The Vice President becomes President
coincident with his resigning the office of Vice President.
After considering this nice Yoo article, I am reminded of one of my favorite Justices, who's often tortured opinions I read with delight. The brilliant and insufferable Judge Scalia was constantly confronted with a dilemma of his own making. He insisted he was an "originalist" -- but of course only when such insistence served his immediate purpose. Thus he maintained that the Constitution should be interpreted as the founders would have interpreted it at the time of its adoption. In other words he presumably wanted us to interpret our Constitution today as we would have in the past at a time when nothing moved faster than a horse. A little reflection on this absurdity will reveal why he was often having to abandon his "steadfast" insistence on originalism. A conflict arose every time an amendment to the constitution was central to a case before the court. He would then insist that he means by originalism that both the original document
and the amendments are to be interpreted as the respective drafters would have interpreted them. So far so good. But of course the Amendments regularly trump the thinking behind the original document when drafted. The irony of the Constitution itself paying little heed to originalism, seems never to have dawned on Scalia. If it did, he never let on.