I do not have the knowledge to write an obituary for Joe, but can add a few anecdotes.
Joe and Callum accompanying Archie Fisher and running him into overdrive at a very early Ballad & Blues event in Iona House at the Boomielaw.
Joe copyrighting with 'new words and music by' any trad song he recorded, including to the irritation of Norrie Buchan a verse of Coulter's Candy Norrie had written just a few weeks earlier to fill out his weekly newspaper song column text.
Meeting Callum years later and being told about Joe's way with the group cosigning a contract.
I just donated a copy of the Joe Gordon Songbook to the archives of the University of the Highlands and Islands.
Enough.