I've engaged her before on the subject. She plainly ignores anything that contracts her views (which is very nearly any piece of scholarship on the Constitution), including the Federalist Papers and the constitution itself. It is absurd.
Indeed, though, you are correct on another count: Madison notes in Federalist 42 that the point of the commerce clause was to create a free trade zone.
There is more to originalism than the majority (and better documented) Federalist opinion, as I am sure you know. One must go to the understanding of all those who ratified the Constitution, including those who held opposing understandings upon specific elements, or held reservations until the BOR was under construction. As you saw in the article above, such monority opinions can develop predominance after long periods of time.