A lot of people have "internet balls" and will do crap because they can be anonymous but wouldn't dare if they knew people could bring about real consequences against them. It's unfortunate but you brother needs to learn there are both good and bad people in the world that range in the intensity of their positive or negative behavior. Sucks he is hurting but it is a minor loss in the grand scheme of things and better to learn this now so he can be on guard in the future.