I have the album Utah did it on, and it says "collected by George Milburn"
a search for George Milburn and 'timberbeast' gets this page where Milburn is credited with collecting a version of "The Big Rock Candy Mountains." in the 1920s.....so I guess we can't ask HIM...

The article also mentions "a Potlatch timberbeast" as one occupation of hoboes....so some things seem to be connected. I wonder if Utah got the song FROM Milburn.