You can see that the adjacent rock is higher, so he tried to land lower, which is quite steep and tried to use his one hand to grab the rock.
Look carefully at him. He has a camera, a tripod and also a plastic bag, all on his shoulder or in his left hand. Only his right hand is available to grab the rock and counteract the weight of his stuff.
He lands low and both his right hand and right foot slip away... At that moment I take this shot.
He pushes his body against the rock, waits a few seconds, throws his stuff on to the top, climbs up and walks away……….".