Thanks for the extra information about the original poem's provenance. I had thought of posting the Singabout article ... but I felt that wasn't appropriate in a memorial thread to Slim Dusty - who, after all, simply did a great job of popularising a song by his mate Gordon.
At the time the item appeared in Singabout (circa 1961 ...?), the gripe was not with Slim, but was part of a general one about the dubious copyright claims, mostly promoted by recording companies, on traditional and "borrowed" songs. (The Bush Music Club had, just about that time, had a run-in over a recording company's A & R man "claiming" copyright on a traditional version of Charlie Mopps"!)