The idea that citizen at birth equates to natural born citizen ignores the word natural.
If the intention was otherwise, they would have simply said a born citizen, or a citizen at birth or born a citizen.
So it is clear they intended something else. So - what does the word natural mean in the context of natural born citizen? There are two types of law. There is positive law - this is man-made law, such as the Constitution, laws from Congress, state law, local ordinances, and so on. And then there is natural law - this is the law of nature, or the divine."
Indeed. Simple logic dictates this.
And, speaking of natural law: Our Declaring Independence, and the founding document itself is based upon natural law principles.