Here's the actual treaty in which the US got the rights to the Canal Zone:
Key section is "which the United States would possess and exercise if it were the sovereign of the territory within which said lands and waters are located".
The US paid for the "use, occupation and control" of the territory, it did not "become" US territory.
Fine.
Here’s the paragraph that I refered to, I went to it from the link I posted to you. It is there.
2. Sen. Lindsay Graham, taking McCain’s side, notes that McCain’s father “was posted [in Panama] on orders from the United States government.” (One might also argue that the Canal Zone was not truly “foreign” as a U.S. possession at the time, but we can leave that out of the analysis.) But this should not be dispositive. Whether U.S. citizens are overseas on military or diplomatic assignment, or on private business, or merely tourists; whether their children are born on embassy or military grounds considered “U.S. soil” for some purposes, or are born unquestionably on foreign soil—these cannot be the considerations that dispose of the question. It is their parentage that matters. The laws of nations differ as to citizenship, and while some countries will recognize children born on their soil of sojourning parents as citizens, others will not. Would we say that the child born of U.S. parents in a country according that child no citizenship is not a U.S. citizen either, and is therefore a citizen of no country at all? That is an absurdity that cannot be imputed to the Constitution. While the framers may not have anticipated significant numbers of American military and naval forces on extended foreign assignments, with whole military families stationed overseas and children being routinely born, it is inconceivable that they could have intended that a) U.S. diplomats’ children be ineligible for the presidency due to the accident of overseas birth, or even that b) the children of private citizens traveling abroad be likewise ineligible.
I agree with the author.