The argument that Congress made, was that McCain was born on a US military base (but evidence shows he was not), and that the base was US territory, so he was not born in a foriegn country. So, they concluded he was still born on US territory, or as Vattel would say, ‘in the country’. Therefore he was a NBC.
When Congress concluded that McCain was a NBC, they did so by backing the ‘parent citizens’ + ‘in the country’ = NBC, definition by Vattel.
“Whereas previous presidential candidates were born outside of the United States of America and were understood to be eligible to be President; and”...