WTF? When I was an A&P with USAir, (now American) we never, NEVER, towed an aircraft without someone on board riding brakes just for this reason. If the tow bar broke, and they occasionally did due to having a couple strategically placed aluminum bolts as shear pins to prevent damage to the nose gear, the tug driver was to get out of the way and away from the aircraft and the brake rider was to, well, apply the brakes. This guy was lucky!