Actually, a Federal Marriage Amendment (whether one favors it or not), if ratified, would be federalism in action since three-fourths of the states are needed to approve it.Really? No, really? I've never heard Levin described as a prankster or satirist, and even if so, this only qualifies ironically.
Federalism, loosely defined, is the practice of letting the 50 states handle an issue as each of them sees fit instead of having a solution imposed from the central government in Washington, DC. An amendment to the Constitution that would impose law on all 50 states, as the Federal Marriage Amendment would do, is exactly the opposite of federalism, regardless of how it is enacted.
It matters not at all that the amendment would be passed by the states, as Levin points out. The effect of the amendment would be by definition anti-federalist, so why would the process by which it is enacted be at all relevant to the question? Using the federal amendment process (as opposed to the Congressional one) to circumvent federalism cannot be considered federalism. If you pardon the Godwin, that's like saying, "But Hitler was elected!", or noting that Jim Crow laws were duly passed by the people's representatives in several states. Applying democracy to a bad or just plain evil idea doesn't make it acceptable (that's why a republic with separation of powers and checks & balances is ideal), and using federalism to pass anti-federal law doesn't make the end result federalism.
I would think that a professional lawyer and former Reagan administration officer would know that. So maybe he was being too clever by half. I hope.