Some people just like to argue and like to fool themselves into believing they have made an irrefutable point.
Your post is ridiculous. What you have referred me to is a series of didactic, pedagogic pieces written in a pseudo-classical style intended for young students learning the violin. I have run across more than one of these in the Suzuki teaching series my son went through when he was about 9 years old. In fact a recording of his playing a Seitz piece, one of those on this page, at that age is my ring-tone for him.
If it looks like a duck, quacks like a duck, sounds like a duck, and waddles like a duck and has all the indicia of a duck, it's a duck.
Similarly, Ashokan Farewell has ALL the indicia of a folk tune. It's a folk tune.
Please, let's all go on to something else.