See#503
"In the case of the United States." That means -- plainly; inarguably; irrefutably -- we are E-X-E-M-P-T from having to surrender our authority, re: trade, to the UN. Case closed. Period. End of sentence. Full stop.
You don't get to cite only the scariest-seeming, ooga-booga-portions of the document, whilst simultaneously squeezing your eyes shut and pretending with all your might that the other portions don't exist, given that they're lancing your argument like a boil. The words say what they say. Cope.