“Kabar would say that citizenship didn’t attach yet, because the person hadn’t submitted evidence and requested a grant of citizenship.”
The citizenship is granted at birth and not when it becomes vested by satisfying the conditions needed to receive recognition and vest. Think of it like the inheritor of a vast estate who must prove identity and satisfy the conditions of the codicil before the probate can settle the rights of the estate upon the inheritor claimant.
You haven't answered my question. You are posing an alternative question, that of when the rights are recognized, and in that regard, I agree. They aren't recognized until they are recognized. The issue under debate is whether or not the right exist before it is recognized.
In inheritence, we are dealing with a transfer of property. In citizenship, we are dealing with a personal attribute, something that can't be taken from one and given to another. Does "the one" possess US citizenship at birth, or only after applying for it?