Right, and Scalia and other textualists feel the proper way to do that is to look at the words of the law as written.
There's nothing in the words of the 14th that speaks to the immigration status of the child.
You agree we must understand the law as it was understood by the lawgiver but then, improperly IMO, apply textualist views to the matter (Scalia's).
Legislative history in this instance is not relevant. Neither is the intent of the Constitutional language or the fact the language does not refer to immigration.
As you stipulate, the issue is what was understood by the authors of the language they used (which is the concern of originalists, I would add).
IMO, the dissimilar language used in the two references to jurisdiction makes it clear there is no ambiguity in the use of the first ("subject to"), that the reference addresses citizens.
Thus, the second reference ("any person...within") clearly provides that any entrant shall be denied Constitutional protections of due process, equal protection of the law, etc
Neither reference, of course, should be construed as conveying unspecified rights or benefits such as immunity to criminal laws, to any unnamed individuals.
Under this view, an anchor baby born within as the result of unlawful entry and yet under the jurisdiction of a foreign country is not automatically entitled to citizenship.
It has been fun, you can have the last word.