If you're referring to this post:
" I think that’s one thing people fail to grasp. The Republic of Vanuatu could pass a law declaring every member of FR its citizens, and that would not mean we “relinquish” our original citizenships.
"No, but it would mean you relinquish your original citizenship if you subsequently apply for a Vanatuan passport."
I would think it's obvious. The Republic of Vanauatu could pass a law declaring every member of FR its citizens, and it would have no effect unless and until you decided to take action upon that declaration and apply for a Vanuatan passport. Your action (and their acceptance of your application) would be a de facto renunciation of your US citizenship under the sections of the USC already quoted.
But what does US law say as opposed to how we might think things ought to be?