from what i can see in the clips, justin was at the tip point at the very top before he backed down.
he got there when his driver side rear tire shifted to the passenger side in the groove he was climbing up.
the actual tip happened when he backed down on the 'new' shift line and that rear driver tire contacted the ground. with the speed of the reverse, the heavy front end still had inertia, so it bounced with the shocks and kept going, a la flipping off flipper.
i doubt he could have come down any slower, so that's why i say he was at the tipping point before he even reversed. the only way out that i can see from video would have been not going anywhere and await a strap up front to pull through.
i don't believe sway bars would have had any bearing on this. it was all heavy front weight and shifted bad line on the rear driver tire. at that point, newton had already owned justin and the toyota.