We are, of course, free to disagree with that understanding.
It may even be wrong.
Regardless, it is what it is.
I personally think that if the founders had elaborated on this issue, they probably would have explicitly stated that an NBC would need two citizen parents.
But they didn't. And my opinion doesn't drive the issue.
So unfortunately, it is what it is.
This begs the question, can this really go anywhere? If not, is it beneficial to press it?
The founders didn't need to elaborate. To them, "natural-born citizen" was a term of art with a settled definition:
“The natives, or natural-born citizens, are those born in the country, of parents who are citizens.”
Book I, Chapter XIX, part 212, of Emerich de Vattel's Law of Nations.
The Law of Nations was used as a guide and reference by the Founders while drafting the Constitution. Their personal letters are filled with references to it.
The Supreme Court also cited Vattel repeatedly. It's considered one of the references to determine "original intent".
But, the Supreme Court apparently doesn't want to settle this particular issue, and would rather let it play out in the political arena.