You're missing the pivotal point here. Until it is confirmed that you are a US Citizen, you have no rights except for those granted under the Geneva Convention. Your normal rights as a US Citizen don't start until you are across the border line from no man's land to the US.
There is no destination you can travel to where your American citizenship ceases to exist simply by virtue of your location, including North Korea or outer space. But hey, if you're convinced otherwise then I guess I'll let you deal with living inside your own self-constructed cage. Perhaps some day the meek and subservient will inherit America from the free and the brave, but if that day ever comes it won't be a country I'd ever want to live in anyway.
It's not a matter of your American citizenship ceasing to exist. You are and will always be an American citizen; unless of course one decides to renounce their citizenship.
This issue is that when your standing in that line asking for admitance into the US, your citizenship is uncertain. The fact that you're carrying an American passport means nothing. It could have been lost or stolen or even forged. In the eyes of that officer and under US laws concerning entry to the US, you have no citizenship of any country until you can prove that you do indeed hold citizenship in X country. You are in effect, a man without a country until you prove it to the officer.
And therefore the only right you have are those guaranteed under the Geneva Convention.
I've looked into this rather extensively after I wrongly got thrown out of Canada. Now granted I'm not a citizen of Canada, but their laws are remarkably similar to ours. And trust me it was pretty scarry sitting there knowing that I didn't even have the right to call a lawyer, that I would loose my car and its contents, and land in jail. And all without much fanfare.
Perhaps because my story was the truth and they couldn't shake me, perhaps maybe I just got lucky, I'll never know, but instead the supervising agent instead decided to return me to the US and ban me from entering Canada for a period of 1 year.
But again, after that I did considerable research into this issue, because I never realized that the only rights I had were those granted under the Geneva Convention and that assumes that the country your traveling to actually signed that accord. If they didn't, then you have even fewer rights.
You don't have the rights of a US Citizen until you are able to prove to that officer that you are indeed a US citizen! And that's not a 9/11 thing; it's always been that way. It's probably gotten harder to prove that you are a US citizen since 9/11 and the officers are most certainly more suspicious of you since 9/11. But make no mistake, you don't have citizenship rights when you show up at a US Border control point.