It's people like that that really have me concerned with the way this game might be going. While some would call them greifers/agitators/trolls, they would probably say they are just PvPers that are following the rules of the game. An mmo-sociopath. I've seen them since early days of UO, and I am sure they were there even in Diablo II and earlier.
Their fun is ruining everyone else's fun, and eventually, either it kills the game, or the entire game turns into this...the lowest common denominator of cyber-dweeb.
I am all for consensual PvP. I think PvP should be part of the game. I also think it needs to be an OPTIONAL part of the game. You should not have to deal with people like this, like people who kill your ship in EVE in a high-sec area so their buddy can salvage both your ships, like people in WoW who used to flag themselves PvP and jump on top of your toon so your AE would hit them and flag you too (when you didn't want to PvP).
Have several systems be PvP areas. Have items just as good in those areas are can be obtained elsewhere...maybe even SLIGHTLY (10 percent) more abundant but not much more. That way all the people that want to PvP can do so, and those that don't want to can avoid it without giving up 90 percent of the game.