I'm amazed at how pisspoor Circle's handling of Poloniex has been. They've pretty much done nothing with it. Even if they're only placeholding they should at least make an effort for the existing users.
As for this, they allowed this to happen. They should be picking up the bill. Stuff like this will only speed up its drive into oblivion. In a space filled with utter waste $400 million for this looks like one of the biggest cash bonfires of all.