"Subjects" cannot run for King, so how is that germane? Native born has much in common with subjects. Natural born implies something more than mere citizenship.
Great point. It exposes the BS of those who claim that the Founders followed British common law on this issue. They did not.
It's germane because we derived our basic legal understanding and models largely from English common law. To quote the US Supreme Court:
The interpretation of the Constitution of the United States is necessarily influenced by the fact that its provisions are framed in the language of the English common law, and are to be read in the light of its history.
In America, we were to be not "subjects," but "citizens." That's the difference.
There are other freedoms and privileges of citizens that subjects do not have.
So yes, there's a difference between "citizens" and "subjects" between the two countries. In US v Wong Kim Ark, however, Justice Gray used their determinations of "natural born" (an adjective phrase used to specify a certain kind of either subject or citizen) as a model for ours.
He quoted Justice Swayne in Rhodes:
All persons born in the allegiance of the King are natural-born subjects, and all persons born in the allegiance of the United States are natural-born citizens. Birth and allegiance go together. Such is the rule of the common law, and it is the common law of this country, as well as of England. . . . We find no warrant for the opinion [p663] that this great principle of the common law has ever been changed in the United States. It has always obtained here with the same vigor, and subject only to the same exceptions, since as before the Revolution.
Gray also further quotes:
And if, at common law, all human beings born within the ligeance of the King, and under the King's obedience, were natural-born subjects, and not aliens, I do not perceive why this doctrine does not apply to these United States, in all cases in which there is no express constitutional or statute declaration to the contrary. . . . Subject and citizen are, in a degree, convertible terms as applied to natives, and though the term citizen seems to be appropriate to republican freemen, yet we are, equally with the inhabitants of all other countries, subjects, for we are equally bound by allegiance and subjection to the government and law of the land.
So it's germane.
All the more so, since all but 2 of the Justices concurred with the majority opinion by Justice Gray.
I will add, however, that we’ve never had a specific determination by the USSC of the definition of “natural born citizen” for the purpose of being President. I personally think the Wong Kim Ark ruling gets pretty close, and think that on that precedent the child even of two resident alien parents would be qualified. Although perhaps a dividing line might be drawn if they had not established a permanent residence.