I dunno... I think this excavator operator has a good chance of winning that argument.... I can only say... wow... Yes he is following guidelines... a 60 degree slope for the first 5 to 8 feet at the top of the ledge he has cut and is sitting on. But honestly it is not easy to tell when you cutting into the face above a fault in the sediment layers. (ie an ancient creek bed that has filled in, or damage to the structure from earthquake, etc.) If you happen to drive onto that fault as you progress... your likely going to end up at the bottom of that chasm. An excavator that size typically weighs between 80,000 pounds (36,287 kg) and 110,000 pounds (50,000 kg).... so regardless, if things start to give way...once it starts moving down hill... it will accelerate quickly and nothing will stop it. The operator is unlikely to survive even if the cab were to miraculously stay intact. The G's would be horrific at the bottom with that much weight coming to a sudden stop.