There are no snake keepers that are in the wild to prevent ball pythons from eating all kinds of non intentional stuff. My ball python used to be on aspen, and he usually ingested quite a bit of substrate because of the fact that the damn stuff just sticks to the rat whenever the rat has water on it's coat. As long as it isn't a huge ball of it, it will not kill him.
The python has to digest bone, fur, claw and tooth material, a little bit of substrate will not harm him.