Certainly not in regard to 49 of them. Vermont is not a people.
I don't think all peoples means a race or ethnicity, it just means people.
The definition of what constitutes a people is hazy, but it does say peoples rather than people - and it's not as if these were near-homonyms in all other languages. There is nothing in there that could in any way or form be used to support the historical US "States Rights" lingo.
I disagree 100%, in the case of the South in particular, you could argue that southerners are very much their own "people" with their own culture and customs. Then there are states like Utah (heavily Mormon) and the guy who mentioned North Dakota most up in those states are Germanic.
I still believe that peoples means any people who want to be free to run their own affairs should be able to, I don't think the UN has a scale of which people deserve freedom and which do not.