Sorry but there is a world of difference between getting a ball from a garden and someone attacking the ball retrievee with a spade presumably in daylight as in your presumption and two persons breaking into a house at night armed with a screwdriver and an elderly man defending himself and his wife and accidentally stabbing someone to death in the act of self defence. Its nothing to do with far right redundancies either so you would be better off stop trying to twist it into something it is clearly not. Its just common sense.
But it isn't just common sense when it comes to law in particular when someone is killed. He was defending himself I agree but at the same time but there is a fine line and I am certain that this will come up in the court case.