Trick question, as you well know. It was most recently decided during McCain's Presidential candidacy. The consensus was he was born of US citizen parents (plural), regardless of of location. So it's really a two-legged stool, isn't it?
I think you are misconstruing it. His parents were U.S. citizens, but he was born on a military base?
McStain was born on foreign property over which the US had sovereignty at the time.
Your slam is invalid.