What he says about Keegan, Pearce and the dressing room at the time, doesn't surprise me at all.
Regarding the incident with Dabo, I heard from someone connected with the club at the time, it started from Barton's interview on GMR with Cheeseman, where he said the players were not good enough. True, but you obviously can't say something like that publicly while playing for the club, so you can imagine how that went down. Not long after that interview we lost 2-0 at home to Villa, with Barton missing a penalty to make it 1-1. In training the week after, Barton and Dabo had a few tussles during the training match, words are exchanged, then Dabo picked up the ball put it on the penalty spot and smashed it into the top corner, he then says to Barton 'that's how you do it and that's quality', obviously a reference to Barton's interview. Barton just completely lost it at that point.