This is another problem of the block. It makes "legit" PvP like piracy and bounty hunting much more difficult.
I don't think anyone would say that's an illegitimate PvP, along with the PP, CZs, BGS wars and probably anarchies as the "anything goes" areas. But attacking a unarmed/unpledged/no cargo/newbie/d-rated explorer has no other motivation except "lol, ship go boom" and to waste other people's time / ruin their enjoyment of the game.
I've never seen a RPing pirate and I'd quite welcome an encounter with one of them, but whenever I was in Open it was only o7 or running away from my hauling Python (!) or (once) a situation right out of the movie "The Warriors": "come out to plaaaay" by three FdLs trying to get on the tail of my unarmed, no cargo Cobra. (the exact com lines were "come closer so we can shoot you"...)
In this long thread there were two workable solutions offered:
no limit on PGs, with proper administration and control
or
instancing PvE/PvP flag that has priority over all other instancing factors so you simply get instanced with those who have the same flag enabled (and proper controls and sanctions for the abuse of those flags)
Either would work, except for the "lol, ship go boom" gankers who would probably end up in instances with other gankers only and a few brave souls who find being attacked for no reason a thrill.