"True griefimg"? Killing by itself is not harassment. Frontier has said this many times. Beyond this Frontier has said it's all about "context". So "harassment" is currently and unfortunately vaguely defined. The only thing Frontier are 100% clear on however is that verbal abuse is unacceptable.
It should also be noted that killing in game is being addressed by Frontier's game mechanics. So the degree to which repeated killing is considered "harassment" is already penalized with bounties, harsh police response, and added Rebuy fees. If you're looking for punishment for in game actions that goes beyond the scope of mechanics, then you risk becoming the harasser rather the harassee. That is the line in the sand. Keep it in game, keep it clean, snd you're in the in the clear.
There's always block if anyone feels the need to remove an irritant. I get rid of the station rammers that way.