He's not there to grief you, he's there to help his allies. You have allies too, that you can ask to help your PK. That is a difference.

What Rogue does in PK is not the issue, its his actions outside of PK - summoning mobs, plaguing them, trepidation, causing xp deaths and looting lowbies afterwards - its just griefing masquerading as RP. There is plenty of constructive stuff he could be doing with his RP - for example, Jayundar helped a few of us nightreavers rank with shields and stuff, and did it with style - she kept us on our toes with lots of creepy implied threats and evilness oozing out of every pore, and sort of turned us against each other in the process

One is a PK issue, the other is what he does outside of PK. They're very different.