I would say this is an exploit because you can do it on a very poorly geared 120 and still get the kills.
This relies on you having a slow/stun/root, just anything that can prolong the time a horde player is in the area for, the nets that dismount are fantastic too! You want to make your way to Arom's Stand and position yourself off to one side of the main gate (so you are out of sight). Just wait for a unsuspecting horde player to run through and begin to slow/dmg them as the guards pile on them You will usually get 1-2 kills every 5 mins, usually more if your on a busy server.
Imgur: The magic of the Internet
SG.