Purely from a legal perspective, my problem with Roberts' opinion is that he essentially rewrote Section 1 of the 14th Amendment to read that children born in the United States to anyone ARE subject to its jurisdiction and are therefore citizens. The plain text is that there's something else needed besides merely being born in America (or, more specifically, the United States, which legally is different from the American territories). That's why it says "AND subject to the jurisdiction thereof" [emphasis added]. But Roberts makes it into a tautology. I am born here, therefore I am subject to its jurisdiction.
Yes, he further goes on to explain through English Common Law that being present in a territory therefore means you are subject to its jurisdiction, but that's just furthering the tautology and not explaining why the authors of the 14th would insert "AND subject to...." if they thought it was self-evident.