I keep seeing those ruts on the driverside of the road, I easly imaging a gust of wind hitting the passenger side of the TC hard enough for the driver side of the truck to be pushed into the rut. That in itself is quite an angle and load on the tie-downs. When the bed of the truck hits the bank, and the truck/TC is already at an angle due to the rut, the truck stops its roll but the TC (top heavy) does not. I cannot imagine any tie-down that could take that amount of force, regardless of the manufacture.
I am not suggesting a fault here, but simply under those circumstances (wind/road) it is risk we take. When we see big truck on their side due to wind, it should be obvious.