If, hypothetically, McCain's parents were both American citizens and neither were in the military at the time he was born in an American territory, he would still quilify as a "natural born citizen." That would be almost the exact same case as the one regarding Barry Goldwater (born to two citizen parents in Arizona Territory in 1909). The Goldwater case was decided in his favor by a federal court in 1964.
Do you have more details on this case? I have previously asked about who would have standing to bring the natural born citizen question to court without receiving a satisfying answer.
ML/NJ