If someone pays attention, they realize foreign citizens are not subject to the jurisdiction of the United States. Of course, they can be prosecuted for crimes, but the embassies for the citizens are safe havens, and they might even be allowed to leave under the protection of diplomatic immunity.
What does this have to do with the 14th Amendment? Its the part about jurisdiction. Foreign citizens are not under U.S. jurisdiction, and even if their child is born here, they are still a foreign citizen just visiting. Therefore, they are not automatically a U.S. citizen.
This is easy stuff. How anyone can think otherwise either indicates they're as dense as a box of rocks, or have an agenda to subvert the laws of the United States.