Have to Agree with Will Fly. If you like a song and enjoy singing it in whatever fashion you chose then do so. That in my belief is the way folk music works, there are no rules.

As for the accents in the Southern states I believe they developed from a much wider range of people than just us working class Brits. However regarding PFR's mention of Somerset accents,there was an excellent series on television some years back about language which included fisherman from the Georgia Sea Islands who definitely had strong traces of West Country.

Re the OP it's obvious the listing in the magazine is crap. Music isn't (or shouldn't be) a contest.
And just for the record I firmly believe Blue men can't sing the Whites unless you believe that the blues is just a chord sequence.