It was an out of control and untamed horse, and a horse like that is far more dangerous to a human, than the other way round. The horse would have caused more harm to avni-neil if they hadn't reined him in with the rope. And they didn't harm him at all. Harming him would be if they hit the horse, or shot him to save themselves, but here, all they did was throw a rope around his neck and rein him in, then tie him to the tree, which his how you are meant to deal with a wild horse like that when it is out of control. That's how even the professionals deal with horses, as you are forgetting as well that horses necks are not fragile like humans, and are incredibly strong. It is through their neck that you control them.