That exception comes from the fact that, I'm guessing, no diplomat or their children have sued over it.

If they have, I'd love to see exactly where a prior SC decided that it's constitutional.

If you are an originalist, textualist, or even just standard jurisprudence believer then it's crystal clear what the 14th meant. The only reason for any question about it is because a large portion of people hate the fact that someone can get citizenship by being born here.

The dissents violate the supposed judicial theory of these justices. It shows naked partisanship.

I mean, aren't diplomats immune to US laws? Literal "diplomatic immunity".

It makes sense to me to say that they do not fall under US laws and US jurisdiction, and their children likewise.