I roam around, and find other survivors. They, too, are citizens. We build shelters, and wonder what going on. We wonder if any help is coming from the fed. In the meantime, we build shelters, and work to survive.
After another 6 months, we basically realize there is no help coming any time soon, so, as is our right, we form our own government, based upon the values of the USA. We have elections, and setup positions. We are the township of Snarf. We are all Americans.
Your claim is that we toss aside "American", and we are now the Nation of Snarf.
And I disagree.
Now, same scenario. Crawl out. I enslave nearby survivors, and eat some. I meat some like minded killers and we group up, enslaving and killing. I obviously have no morals nor care for the rights of others. My group is lead by me with a iron fist.
Am I a citizen? Yes. But I am also a law breaker, with no regard for the rights of others. IF the fed, or state govt swooped in, I would be punished. If I meet others who respect the values of others, would prolly war them. I am my own faction, with my own rules. I may even declare myself my own nation, and I may claim to be ruler of the entire land. I'm obviously full if it, but... I was a citizen, I just decided to no longer honor those values.
That is where I'm coming from in a nutshell.
Snarf snarf.