He argues based on allegiance, and where does that allegiance come from? From birth, and minors still owe allegiance to the country of their birth.
“Mr. Smith being, then, at the declaration of independence, a minor, but being a member of that particular society, he became, in my opinion, bound by the decision of the society, with respect to the question of independence and change of Government; and if afterwards he had taken part with the enemies of his country, he would have been guilty of treason against that Government to which he owed allegiance, and would have been liable to be prosecuted as a traitor.
If it be said that very inconvenient circumstances would result from this principle, that it would constitute all those persons who are natives of America, but who took part against the revolution, citizens of the United States, I would beg leave to observe that we are deciding a question of right, unmixed with the question of expediency, and must, therefore, pay a proper attention to this principle. But I think it can hardly be expected by gentlemen that the principle will operate dangerously. Those who left their country to take part with Britain, were of two descriptions— minors or persons of mature age. With respect to the latter, nothing can be inferred, with respect to them, from the decision of the present case ; because they had the power of making an option between the contending parties ; whether this was a matter of right or not, is a question which need not be agitated in order to settle the case before us. Then, with respect to those natives who were minors at the revolution, and whose case is analogous to Mr. Smith’s, if we are bound by the precedent of such a decision as we are about to make, and it is declared that they owe a primary allegiance to this country, I still think we are not likely to be inundated with such characters; so far as any of them took part against us, they violated their allegiance, and opposed our laws...”
It takes a powerful leap of imagination to suggest Obama Jr owed allegiance to the UK or Kenya as a member of their society, assuming he was born in the USA with an American mother who then raised him with no help from the father.