I happen to agree with your position. But, the majority opinion in Ark goes a long way towards rewriting that definition, if it doesn't get there entirely. And, as others have pointed out, the Constitution doesn't define "natural-born", it just employs it's use. It would be the prerogative of SCOTUS or the legislature to modify, change expand or limit what the contemporary definition is or isn't.
What's important, is it would seem that Scalia, Roberts, Thomas and Alito all think it(Ark)does define it in such a way that it supports Obama's presidential eligibility (assuming of course he was actually born in HI), or they wouldn't have denied cert in the Donofrio case. Roberts made it clear in his confirmation testimony about his reverence for stare decisis. Roberts, nor anyone else on the bench - at any level - hasn't the appetite for revisiting Ark, or any number of cases that upholds or reinforces Ark.
Nor do I think they will take it up unless someone can produce evidence Obama wasn't born in Hawaii. Once the Taitz birth certificate blows up that'll make it even harder.