Getting my very own Stargate makes me happy.
You CAN port the whole raid. He was talking about class stacking. If you have 5 warlocks: 5*5=25. The problem isn't necessarily that you COULD port the whole raid, it's that it would require 5 Warlocks to do so. If this ever became required to down a boss, it completely goes against the "bring the player, not the class" philosophy.