Congratulations to Ensidia, and anybody else beating final encouter of WOTLK, job well done!
The circumstances are bit unsettling, however, such a major bug should not get into live version in the first place. Of all encounters in WOTLK, this one should have been thoroughly tested. No matter how obscure the initiation process for this bug is it should have been spotted and fixed before releasing to public.
It was mentioned earlier in this thread, Ensidia and other top guilds will hardly miss anything this major when they check their logs and parses.
It comes down to point whether you expect that players will police themselves, effectively doing Blizzard's job. I would assume that GMs were watching Ensidia progressing on LK. If there was such apparent bug they should have disabled LK encounter for them and any other guilds on him at that time to keep the grounds even and the encounter still enjoyable in its full complexity.
However, anybody saying they should have stopped attempting LK is just fooling themselves, or lying to fuel hate against Ensidia. Im sure no guild seriously aiming for world first kills would stop their attempts on something not publicly acknowledged by Blizzard.
I dont want to ignore implication of the bug and its fast hotfix, therefore, I would appreciate Blizzard--not Ensidia restricting themselves--simply does not allow ICC HM being accessible in next reset for anybody for at least one more week.
First part of race is over, both 10 and 25-man achievements are claimed, we can now focus on HM. Blizzard should make all effort to help to settle the situation that their carelessness caused.