Just a few words in JJs defense: He recorded in a time when one couldn't sell a record of this type of material unless it was called "folk". A bit later he realized that he couldn't make any money from other people singing his somgs unless he claimed authorship.

Certainly, his claims are not reliable from a scholarship perspective. But is this so different from Oscar Brand copyrighting Yankee Doodle or Pete Seeger copyrighting Cindy? In anycase, he wrote (or adapted) and introduced some fine songs.