The OP cannot understand this and cannot believe that there are people in this world that have unreasonable aversion to being touched in any manner by another person. Not to mention that the so called Tweeker ( the OPs professional diagnosis of the individual ) could have perceived the so called "pat on the back" as a hostile attack.
The OP got Lucky, he could have ended up with the crap stomped out of him and left laying there crying for the police.
The OP should have just ignored being called an asshole and went about his business. It could be that where he tied his dog caused the " Tweeker" to trip on his way into the truck stop or interfered with sidewalk traffic in the immediate area.

