Or, was the cause of the accident that the pilot did not maintain positive 'G' during the entry to the maneuver?
Quite possibly. I was a few miles north aerobatting the Chippy at the time so only saw it on video, but (in my view) respected based aeros pilots who witnessed it were critical of the technique being employed for 'wing-overs'. There was no doubt a carb issue, but was it primary to the tragedy?