That would be a custom feature which goes againts the servers wishes. World PvP and ganking low lvl's is part of the game and there is a whole thread in wich people disscus this. Most common answer is that people like to bully each other in-game without getting punished because they can't do that in real life.
having RDF disabled is considered to be a custom content, but unfortuantely delusional nostalgia is what the server wishes
personaly i never had problem with griefeing, most of the times i see a high level he waves or waveback, one even helped me with grouped mobs
but real griefers should be banned without a doubt, or warmane should work on some way to punish them
it gives the server bad reputation, it pushes people into quitting, and its a bad experience for both players
My question to you Xravi is what do you do against blooks like me? Ya see, i'm a multiboxer and currently level 5 hunters on ragnaros and if i see a horde out there leveling i send in my 5 pets and sit back and AFK and watch the horror as it happens and it is beautiful and that's against players the same level as me. I was 60 dive bombing horde and wiping them with in seconds, so ya see, your idea is worthless as there's always ways of getting around such mechanics as level restrictions, also twinking would be a great way to get past such silly restrictions.
Sorry you're having a tough time out there mate, but cheer up. Soon enough you'll get to end game and be able to enjoy sitting in dalaran just like everyone else.