It isn’t clear at all to me that “subject to the jurisdiction thereof” doesn’t include the children of at least some non-citizens. The “author” doesn’t get to decide what it means. The citizenship clause isn’t the law because Senator Howard said so. It is the law because Congress voted to propose it and the state legislatures voted to ratify it. The question—which would be answered by a court—is what did THEY think it meant when they voted to propose and ratify it.
That's why legislation is preferable to an order. Personally, a non legal professional in any sense, I look to the situation of natives after the amendments passage. Born here, on or off the reservation, not citizens. Until Congress acted. This tells me jurisdiction thereof refers to citizenship in a foreign nation/jurisdiction. The fact than employees of foreign nations children born here don't become citizens tells me the same thing. As much as I like discussing things like ex parte Crow Dog, which lead to the major crimes act of 1885 relative to the jurisdiction issue of sovereign tribes, the relationship to citizenship issues is beyond me. But from my common sense perspective the fact that Congress had to act in 1885 to claim criminal jurisdiction over those not subject to our nations jurisdiction, and had to act again in the 1920s to allow citizenship to those same individuals born in the US but not under our jurisdiction, tells me this is within the purvue of Contress, not a 14th amendment issue. None of which matters, the Supreme Court will end up deciding this one.