When the constitution was written, natural born citizen had a different meaning than what Levin is professing. If you were born abroad and your father was not a citizen, and your mother was an underage American girl there were few back then who would have tried to argue that you were a natural born citizen. Those who say otherwise are subscribing to a revisionist version of history.
You are talking about “The Law of Nations.” It was the book that the founding fathers used when defining the phase natural born citizen. A funny side note, George Washington owes the library of New York something like 200k in late fees because he never returned that specific book. They are still keeping track of it,(more for fun than anything else.)