While it may not be as bad as that photo angle would appear, the danger of the ground giving way under the little excavator and the guy winding up thrown down on those large rocks with his brains bashed out seem like a possibility. I am going to let him do that work, and I will watch.
That type of work isn't worth the risk. It makes me cringe looking at it. Coming from a 34 year mining background, I've seen some pretty radical digging applications. This one is the dumbest so far and I thought I've seen it all....