WLD, I'm fine with anyone expressing their opinion on folk music. I began collecting stuff in the early seventies when I was a teenager, from ancient 78s that would tick all Richard's boxes, Irish music, Scottish music, the Morris Motors Band, Sandy Denny, you name it. It's seamless to me.
What I can't accept is music as a rarified history lesson. That precludes adoption, adaptation, nuance and anyone not bright, worthy or gifted enough to do the research. And I certainly don't take kindly to being insulted for wandering into someone's personal fiefdom before I've barely opened my mouth. If there's a guard dog at least put up a sign.