Steve Gardham wrote:

Whilst not impossible, Leeneia, with Niles's reputation and other odd doctored ballads, do you really think this likely?

I would add another point. While this chain of events is possible, it's not really relevant. A version of "Judas" that is revived, heavily rewritten, and set to a new tune is not Child #23; it is a new song inspired by Child #23. It is possible that it was traditional at some college, of course.

What's more, "Mayberry Thomas" is described as a "yarb doctor," not someone who had learned songs in college. So even if the above reconstruction is true (that is, that JJN collected a song based on a traditional song which had become traditional in its own right), JJN still appears to have given false information about it.