The threat generation of Ectoplasmic Distiller was known about in Vanilla, and used by guilds. The hotfix of this is unnecessary not only due to this, but because nobody is being forced to use it. Threat is certainly not a non-issue in Classic, but it isn’t a major issue for many guilds. If anything, the threat generation from this item would be a boon to tank specs that see minimal or no play (bear/prot pally) by allowing them to not have to rely on farming MCPs endlessly or running oom halfway through a fight from spamming GBoK.
That said, I understand the amount of possible cheese for guilds that do struggle with threat. But imo, even with the distiller, those guilds won’t be able to us the distiller nearly as much through AQ or especially Naxx anyway because of the increased player displacement during boss fights. And again, nobody has to use it.
I just think Blizz could have thought about this decision a bit more before insta-nerfing it.