Considering the boss's spike often shoot you up to that platform, AND the ice-block that lets you climb to that platform appears only during this event, I always assumed that it's an intended mechanic.
Trying to fight waves of mobs which spam aoes while being thrown around the room seems kinda hard considering this boss is intended to be doable for a level 78 group.
Also the fact that some of the mobs have a spell that pull you down from that platform, also make it feels like the platform tactic was an intended feature.
