Exactly...that's why I don't fault him. ATs stall with a lot of vehicles on a steep grade (like the gate). They just aren't made for it because who drives on a vertical wall? The right answer is the two foot drive. Hold the brake with your left foot, keep the RPMs up to where the truck stays put. That is your baseline. Using two feet, don't change the braking and use the throttle as your go and stop juice, never dropping below the rpms you figured out to keep the truck at 0 mph. It is a skill that takes practice.