Your point is exactly right.
If the question ever finds its way to the USSC the language of Art2, perhaps along with that of the 14thA, will certainly be given primary consideration (thus, my tagline).
The clear and compelling language of Art2 makes it obvious your point was exactly the concern of the Framers; that was the reason, otherwise the specific clause delaying implementation of NBC as a qualification was unnecessary.
We had just completed a very bloody conflict with England, of course, and such a possibility was uppermost on their minds.
Therefore, and significantly, they expressly rejected "citizen" as the ultimate presidential-CinC qualification and specified the highest form possible, NBC.
If the Framers intended a form higher than "citizen" and it isn't NBC, Deniers ought to ask themselves, what form was it?
It was certainly not "anchor baby", which is perhaps the weakest form.