You asked what Jones's contribution was to this particular campaign, I naively assumed that you meant the actual campaign that was going on.
If you'd read my previous sentence the "this" would not have confused you! Or if you'd remembered your original assertion (which I was directly questioning) that Owen Jones "had done more to call out Galloway than most" everything would have been crystal clear.
Regardless, I've just checked your new assertion that the evidence for Jones calling out Galloway can be seen "in his book". I've read two of them and have them in front of me now. In 'Chelsea'* there is a single mention of Galloway - a generous one too. In 'This Land' I can find nothing, even in the chapter on antisemitism and the left. That leaves 'The Establishment', which I've never read and don't have. Is the Jones attack on Galloway in there?
Remember we are looking for an Owen Jones attack on Galloway's politics that is equal to anything done by anyone else, such as Hitchens or Aaronovitch or Blair. In Jones's "printed works", which you also mention, I did find this.
https://www.independent.co.uk/voices/comment/left-should-learn-about-plain-speaking-george-galloway-8498536.html It''s not much of an attack is it? Jones does call Galloway's defence of rape "unacceptable" I suppose. A strange choice of word. But on the whole it's a rather flattering portrait of the old Stalinist.
Does any of this matter? I think it does. Not because of Jones. He's unimportant. But because it's symptomatic of a lingering idea on the left that there's a bit of Galloway that is worth saving. The Jones video from Batley demonstrates this erroneous idea.
*Hilarious! The book is not called that. That's RAWK's autocorrect. But you will know the book I'm referring to.