Once again: They stated quite clearly enough that persons in Wong's situation were natural born citizens. And that was the entire core reasoning of the case.
Minor’s essential reasoning to the case:
“...it was never doubted that all children born in a country of parents who were its citizens became themselves, upon their birth, citizens also. These were natives, or natural-born citizens, as distinguished from aliens or foreigners. Some authorities go further and include as citizens children born within the jurisdiction without reference to the citizenship of their parents. As to this class there have been doubts, but never as to the first.”
By using ECL to broaden the “subject to the jurisdiction” clause of the 14th Amend. to then apply it to domiciled aliens WKA resolved the doubts about “[including] as citizens children born within the jurisdiction without reference to the citizenship of their parents.”
The court could have determined that Wong was natural born but they did not. They determined that he was a 14th Amend. citizen.