I wonder - I would be tempted to try to engage him in converation, ask him why he is training his dogs to be so mean, or as he would probably think - protective - security dogs. What is he afraid of? Not that I'd ask him that directly, but it's gotta be behind this. I'd ask if there's something about the neighborhood that you don't know about that is making him make his dogs mean? And let him know that most people are afraid of Rottweilers anyway, why not just teach them to "alarm bark" a couple times to let him know someone's close, because a couple barks from a big black dog will scare away 99% of people anyway, whether of not the dog is mean!