Well, obviously camping outside Hydlaa is wrong, but realistically, nothing can stop you from swinging your sword at someone and cutting them in half. Doing it in public places - such as Hydlaa - would send people after you. So, doing it in an outside spot - such as the Ojaveda Road - where there is no public, just small groups, it would be safe to slay someone and run away.
Now, I have no idea how they will be able to stop PK zone campers, but as long as they do these kinds of things IC - like maybe searching the woods for prey, and they feast on the meat of a dead Lemur for example - it would be ok.