I consider any attempt to stop griefing is a form of flamebait. After all, we cannot mind control our players in any way. There will always be players who will grief others when either they are frustrated and lack skills to move on, or they are too bored with the game content that exist.
A top skill player could easily defeat 20 players of the same level; thus, level does not influence griefing at all. It's like saying a gun cause violence. No, guns only increase the opportunity to scale violence to lethal levels. Weapons in real life don't cause violence. Weapons in real life only increase the damage cause in a violent altercation. The same is said with levels.
Conclusion: Levels have nothing to do with griefing.