I think McCain is considered born a natural citizen because he was born in the canal zone of a father who was there for the Navy—I think military brats born on bases, forts, or navy yards are considered natural born citizens.
McCain wasn’t born on the base but both his parents were citizens.
But the lawsuit filed by Donofrio claims that both are not natural born citizens under the constitution. McCain, he claims, is a citizen by statute, which does not qualify as natural born.
Confirming my response—Donofrio does not claim that McCain is not a citizen, just that he is not “natural born” as per the constitution.