It’s quite clear.
James McClure was born on US soil SINCE the Revolution.
Such fact, without any regard at all as to the citizenship of his parents, made him a US citizen.
In fact, it made him a natural born US citizen.
You’re right that there was a different rule shortly before the Revolution. If a person was born in the United States shortly before the Revolution, and his parents carried him back to Britain, they had chosen British citizenship for themselves and for their children. If that child didn’t act promptly to return to the United States upon reaching adulthood, he was deemed to have accepted that adoption of British citizenship. But he had a right to return to the United States and take up American citizenship (if he made that choice promptly) because he was born here.
Right. It's not being disputed. It's whether he's a citizen or not. That's why the quote talks about applicable laws. He was only a natural-born citizen if his father was a citizen when he was born in the country.