If not a hoax, then it would seem that DHS/ICS may have overstepped it's authority or is outside it's jurisdiction and is stepping on the Secret Service's and especially the FBI's toes.
The FBI still has primary jurisdiction in copyrights violation cases, IIRC.
What may have happened here is that someone went to the FBI to shutdown the sites, was denied, then went agency shopping and found the DHS/ICS eager to make their internet bones.
This seems somewhat like the FBI and Secret Service inept & incompetent Keystone Kops actions from the 90's when the DMCA was enacted, up to and including going after innocent parties, without evidence, without investigation, based solely on hearsay.
If they are in fact acting outside their jurisdiction, I would hope that EFF and other attorneys give the DHS and ICS a justly deserved roasting in court. But the people who induced the DHS/ICS to do this would get off scot-free, even if they lied to DHS/ICS.