Thanks for the link, btw. The statement is from Olsen and Tribe, in the context of rendering an opinion as to McCain's status as a natural born citizen. As such, it had no need to clarify or disambiguate "both birth abroad to parents who were citizens, and birth within a nation's territory and allegiance" as to whether or not the condition "to parents who were citizens" applied to "born within a nation's territory and allegiance."
I accept that the natural read is as you assert, all people born within a nation's territory and allegiance are natural born citizens. But that statement isn't necessary to reach the conclusion they do.
I notice that they also render an opinion that Obama is a natural born citizen by dint of being born in Hawaii, but absent from their assertion is any consideration of the difference in parentage between Obama and McCain.
They imply, without directly asserting, that McCain would have been a natural born citizen even if his parents were not citizens. But their conclusion urgently emphasizes that McCain's parents were citizens, while not even mentioning the "Panama is US territory" aspect:
... the Framers did not intend to exclude a person from the office of the President simply because he or she was born to US citizens serving in the US military outside of the continental United States; Senator McCain is certainly not the hypothetical "Foreigner" who John Jay and George Washington were concerned might usurp the role of Commander in Chief.
Do you know of any similar opinion or analysis, by Olson, Tribe, or some other scholar, that probes "natural born citizen" in light of a person's father being a citizen of a foreign land? I've been asserting that no such thing was done with Obama, but I wasn't aware such an effort was taken up for McCain, so there might well be one for Obama too.
“Do you know of any similar opinion or analysis, by Olson, Tribe, or some other scholar, that probes “natural born citizen” in light of a person’s father being a citizen of a foreign land? I’ve been asserting that no such thing was done with Obama”
You may be right on that. I am not aware of any brief. Googling only brings up the ‘birther’ stuff and a few law profs with opinions. eg. Volokh conspiracy is a good place for this.
The thing is, most folks (ie law profs) think it is such a slam-dunk that they feel it would be unnecessary. In other words, The US Senate bothered to examine this for McCain but not Obama, and the implications for Obama are that birthright citizenship by being born in Hawaii makes one eligible, end of story.
It would be nice for federal courts to rule substantively on this. OTOH, I am sure it would be 9-0 for “14th amendment birthright citizens are natural-born citizens” at SCOTUS.