It wasn't just the left -- Trump is almost certainly going to lose at least Gorsuch on this as well. And it isn't just location and nothing more. The argument is that "subject to the jurisdiction thereof" is intended to exclude the children of ambassadors and others with diplomatic immunity who literally are not subject to the jurisdiction of the U.S.. So it is location, plus jurisdiction.
Just on plain words alone, it's the most simple argument. Ask "is that person subject to U.S. jurisdiction"? If the answer is yes, and they reside in the U.S., they are citizen. Answering "no, that person is not subject to the jurisdiction of the U.S." means you could not arrest and prosecute them for crimes because you lack personal jurisdiction. For obvious reasons, the government doesn't want to make that argument.
So, the administration had to concede, "yes, illegals are subject to the jurisdiction of the United States", while simultaneously arguing that "subject to the jurisdiction thereof" does not include illegals.
It's a tricky argument to have to make.
Are the leftist citizens of Minnesota subject to the jurisdiction of US law ?
Are seditious and self serving spouses of ex presidents subject to jurisdiction ?
They should be but they aren’t, and so should babies born to tourists.