The alternate argument is that anyone in the US is "subject to the jurisdiction" of the US unless somehow immune, eg, a diplomat. I don't see it as very likely

The alternate argument is that anyone in the US is "subject to the jurisdiction" of the US unless somehow immune, eg, a diplomat. I don't see it as very likely that federal courts today would agree with your argument. Nevertheless, this is the argument I've heard offered in support of the constitutionality of denying citizenship for US-born children of undocumented immigrants. Presumably there is some caselaw to support this? Please feel free to educate me with a citation here.