"There is nothing about this performance that I can see that makes it folk music at all."

I agree, it is not a "folk" performance.

You can sing a non-folk song and still be making folk music, and likewise you can have a folk song and not be making folk music.

For instance, the song "Home on the Range" - since we know the author it is not a folk song based on historic defininition, but it sure fits the catagory of folk music.   The same with this performance. Celtic Women, Riverdance, Bowfire, and other shows of the ilk are not "folk music" performances per se, but they do serve to celebrate folk song.

You are right, Copeland's use of folk song was much more appropriate and respectful, but that was not the point I was trying to make. Folk music has influenced other genres of music and crept into our culture in more ways than we realize.