Dick , Bob can sing as much as he wants to as far as I am concerned.
On a related note I thought it was humorless when Dylan sued Hootie and the Blowfish for building a song in tribute to him from snatches of lyrics from the BLOOD ON THE TRACKS album. They did it affectionately even if poorly and they mentioned him in the song, so as to nod and wink. Bob has spent much of his career "borrowing" a thing or two, admittedly more creatively than Hootie,but, borrowed just the same.
Another example of THE FOLK PROCESS STOPS HERE.