http://i50.tinypic.com/5bsnix.jpg
Here's the map. Colon is not in the Zone and never was. And it really makes no difference, the Zone was part of a foreign country, Panama, and still is.
The location of the hospital is clearly identified and it is outside the Zone. At the time of McCain's birth, it was the only hospital readily accessible from the base.
Take a look at your own map.
Coco Solo Naval Station in the upper right is IN the Canal Zone. Only the confines of old Colon were given to Panama.
I lived in Panama. I know where the boundaries are. Why are you obsessing on your false premise?