DHS should really be focusing resources on domestic terrorism rather than shutting down a few websites. If even one American civilian dies because DHS was busy shutting down blogs instead of shutting down a terrorist group ho will they feel then? Obviously they won't care like usual but still.
DHS is an umbrella organization that includes many organizations that were formerly under the DOJ. Not defending this action, just pointing out that the mission of the DHS is broader than just "fighting terrorism".