@potvorkia - They've stated publicly on their website that:
a) they killed him on 10 man immediately prior to the 25 man attempts
b) they knew the platform should not have been reappearing
c) they knew that the platform reappearing made the fight significantly easier
d) they knew that they should have been killing the adds during that phase
e) they discussed it on vent and agreed that if the bug happened again that they would not kill the adds
f) they made the conscious choice NOT to open a ticket or report the bug in any way.

They also stated that on previous world first kills (in BC content IIRC), they had reported bugs and had them hotfixed immediately so that they could continue the fight without either exploiting it or losing significant time on attempting it. Oh, and they've also stated that they knew that saronite bombs made the floor reappear in ToC. That last bit makes it very difficult to believe that they never considered the possibility that the exact same mechanic might be bugged in the exact same way they had already discovered.

For the record, I don't hate them in any way. (Just preempting the cries of "but it's just the haters who think they should have been banned!") I do, however, find facts important when considering issues like this.