This is only indirectly related to your conversation about SR511, but I thought you might find it interesting. While I was reading Vattel's "Laws Of Nations" for another discussion, I noticed this paragraph:
§ 217. Children born in the armies of the state.
For the same reasons also, children born out of the country, in the armies of the state, or in the house of its minister at a foreign court, are reputed born in the country; for a citizen who is absent with his family, on the service of the state, but still dependent on it, and subject to its jurisdiction, cannot be considered as having quitted its territory.
This is, of course, only meaningful if you accept the notion that Vattel's work was influential on our Consitution (Ben Franklin certainly thought so); Vattel makes it clear that the accepted practice among countries at the time would grant McCain citizenship equal to having been born inside the country.
It's really a loophole for NBC status, since Vattel was clear in Book I, Chapter XIX, § 212. Citizens and natives that a NBC is born to two citizens, in the country. However, according to Vattel, John McCain is qualified to be President; Barack Obama is not.
§ 214. Naturalization.(58)
A nation, or the sovereign who represents it, may grant to a foreigner the quality of citizen, by admitting him into the body of the political society. This is called naturalization. There are some states in which the sovereign cannot grant to a foreigner all the rights of citizens, for example, that of holding public offices and where, consequently, he has the power of granting only an imperfect naturalization. It is here a regulation of the fundamental law, which limits the power of the prince. In other states, as in England and Poland, the prince cannot naturalize a single person, without the concurrence of the nation, represented by its deputies. Finally, there are states, as, for instance, England, where the single circumstance of being born in the country naturalizes the children of a foreigner.
Note that the bold sentence refers to England, whose laws on citizenship were used in the colonies. Thus, Vattel is clearly admitting the English practice as entirely valid and is no way insisting that the new United States of America was obligated to adopt any other manner of declaring who was a citizen at birth than that already in use.
Thanks for the clarification and context.