Rob Natelson is one of my favorite originalist scholars. When he writes something new, I will read it. And I think very, very carefully before I disagree with him. His careful writing and meticulous research is well-regarded. Natelson's scholarship has been cited by Chief Justice Roberts, and Justices Scalia, Thomas, and Alito.
I was very pleased to see that Natelson published an op-ed on the Section 3 debate in the Epoch Times. And Natelson provides some support for the Tillman/Blackman position that the President is not an "Officer of the United States" for purposes of Section 3.
The Constitution of 1788 uses two distinct phrases: "Officers of the United States" and "Office under the United States." Natelson concludes, "substantial evidence . . . suggests" that the phrase Office under the United States "doesn't include elected offices, such as senators, representatives, the vice president, or the president."