It would be jus soli for such a child of an alien father to be a citizen but not for him to be eligible to be President. There the Framer's concern that Scalia mentions would be controlling if their intent were analyzed by virtue of what Scalia himself is saying what their concern was. Scalia would agree with what St. George Tucker explained in his comments about the Constitutional provision at the end of his Blackstone of 1804.
There are clearly those, like Judge Robertson, who don't care about the issue because of their bias, but it would appear that Scalia is not among them, at least from the comment you cite and might well actually apply the law as intended in the Constitution.
I take your point, but that is the entire issue, isn’t it? To what extent did the 14th Amendment affect the original language and framers’ intent? I don’t think that the courts want to resolve the issue and the politicians don’t want to touch it with a ten foot pole.