Yes, so?

I can see no reasonable definition of “canonical” for which that is relevant to the claim that the states are “the canonical governmental unit” in the U.S.

If you mean “responsible for functions not specifically assigned by the Constitution”, sure, but that's not what “canonical” means, and in any case the regulation at issue is arguably squarely within the scope of the Commerce Clause authority, so it would be a dubiously relevant claim even if canonical meant that.