Well, it's no secret that DC had a temper and I can see him getting angry at an ABC exec if he didn't like what they were saying and/or suggesting. But one might suspect that he would have had to really go to an extreme to get the show canceled - execs are probably well used to the runners of their shows taking exception to their suggestions. If they retaliated by cancelling every show when the runners lost their tempers, they might have few shows left on the air. But who knows? One thing, though, is that judging by the stories we've heard from behind the scenes of DS and other of DC's projects, it wouldn't have actually been out of character for DC to have possibly taken a disagreement too far, especially if DC felt an exec was treading on his creative territory.
In all likelihood, though, we may never know the full story of why DS went off. There seems to have been so many potentially contributing factors (ratings not being one of them) and many of the people who might have been in a position to confirm the reason(s) have either passed away already or are keeping mum...