Don't know how I missed this ^ saga; just more fuel for my assertion that almost all bad dogs are made that way by bad owners. That dog is a tragedy waiting to occur. Hopefully you will be able to prevail if/when it happens...and hopefully your other neighbours will step up to support you if you are forced to take drastic measures.
Back when I lived in Onterrible, we had a neighbour that sounded like your guy's cousin. He had a big Doberman that had carte blanche to wander where it wished, and it came freely onto our and other neighbour's property acting very aggressively. I faced the dog down several times with garden tools in hand, and it got to the point where I began to wish it would press the attack when I had a machete or axe handy. One day, the dog made the mistake of coming onto my land, right in the backyard...we lived on adjacent 100-ish-acre parcels, so this was a fair distance from the dog's home turf, but he had come to think of the entire area as "his"...and proved how much of his owners stupidity had been imprinted upon him.
He aggressively confronted my wife and two dogs...and my wife was in tears later when she described how quickly our pair put the run on that tough guy. They pursued him to the limit of their Radio Fence range, where they stopped. The Dobe made it just over the property line before collapsing, leaving behind a lot of blood and a long string of intestine. By the time I got home, he was cool and stiffening.
The idiot owner had in the past laughed several times when I had suggested that his dog might meet a bad end if he didn't begin to control it. I went over to his house and informed him where he could collect his dog's remains. I also informed him that I expected full reimbursement for my veterinary bill...my bigger dog had sustained a cut on one ear that needed a couple stitches. That took awhile, but I eventually got my money. He threatened to call the police and eventually followed through on the threat. I am very thankful for the other neighbours who had, over the past year, called the police to report similar aggressive behaviour on the dog's part and a complete disregard by the owner for the problems his animal caused. They visited, and met our two dogs (who were absolutely calm, friendly pussycats, as always), and went on their way.
One of the cops lived nearby, and we ran into him off-duty in the local general store a bit later. He suggested...off the record... that in cases like ours, the Old Farmers' motto of SSS...Shoot, Shovel and Shut up... is often the most expeditious and efficient solution.