We just made a hotfix that disables the siege damage dealt by Saronite Bombs and the Global Thermal Sapper Charge. The siege damage of the bombs was causing the Frozen Throne platform to rebuild, which greatly decreases the difficulty of the encounter.It is a longstanding tradition for end bosses to be exploited in the most hilariously awful of ways, so seeing something like this isn't all that surprising. Here's hoping nothing else like it crops up.
We'll reenable the siege damage in a later update when the issue with the Frozen Throne is fixed.
Update: Ensidia has released a statement regarding their use of this bug.
Update, take 2: Ensidia's raiding crew has received a 72-hour ban from the game (as well as loss of loot and achievements) for using Saronite Bombs to "bypass The Lich King fight mechanics."