"I'd guess that Steve Roud is very reluctant to play God "
Can I just say that Steve didn't always have this problem
When he got his hands on our recordings he had no hesitation in rejecting 'The Ballad of Jon F Kennedy' (quite rightly)
Anthologists and scholars have always "played God" in song identification, Sharp, Child Gavin Greig.... in saying "this is a folk song - this is not"
You have to do this when you are dealing with an art form or genre

Walter was prone to selecting and rejecting songs in this was himself
We once asked him if he knew 'Farmer's Boy' - his reply surprised (and amused) us   
He said "That song was written by someone who didn't know the difference between wheat and barley"
You can't put it more firmly than that
Jim