It's a clever rhetorical trick, but rather unconvincing.
While it's true that Congress has the power to regulate interstate commerce and that health insurance affects interstate commerce, is that really the problem with the mandate? It seems to me the problem is that the mandate forces people to engage in an activity that affects interstate commerce, just so the Congress can then turnaround and regulate that activity.
Don't take my word for it, here's Wisconsin's own Illusory Tenant, a blogger that, unlike me, knows his way around a law library:
Before the mandated purchase takes place, there is no commerce — and therefore nothing in commerce to regulate. It is only by Congress mandating individuals to make commercial transactions that there becomes something in commerce.I urge you to go read the whole thing.
So the question presents as, 'Can Congress force a private party to initiate the transaction that will bring into existence the commerce Congress may regulate.' If the answer is yes, then it's not on account of anything the Commerce Clause says
Here's Illy-T on AG Van Hollen and the individual mandate.