Griefer hunting or looking for trouble? Taking a mission to deliver a wagon, starting in Blackwater which was a rolling gun battle. And take it to Thieves Landing, which was also a rolling gun battle did not look to have much chance of success. Unless the plan was to get into some pvp all along.
The previous days before I mysteriously was not in your posse, the posse was not showing in the posse list at all and you appeared "offline" for 6-7 days it seemed either you were making poor decisions or looking to find trouble and start a war. Not into pvp all that much myself, after a few kills/deaths I've had my fill and am ready to get back to what I had planned on doing. I took a 5 month break until the offense/defense mode patch came out because players were going out of their way to kill others. Or at least it looked that way from where I was standing. I don't know if the patch really changed things that much or players attitude changed, but it is very easy to avoid player vs player conflicts now if you just use a little smarts.
In the last week as a posseless player I have killed 1 player who was acting strange and looked to be hunting me and I have been killed twice. 5 seconds later I was back to minding my own business and no server war erupted. I get mauled and killed by grizzlies 100 times more than by players. I think trying to run all the grizzlies off the server would be about as pointless as trying to run some random player off the server because I was in the wrong place at the wrong time.
Maybe the players you and your posse seem to be having trouble with are the griefer hunters and you are the griefers. Being chased across different sessions as described by some of your posse members seems much more than a random killing.