Everyone seems to have forgotten (or not noticed) that DHS similarly put out a report on potential left-wing extremist terrorism.
DHS/Office of Intelligence and Analysis defines leftwing extremists as groups or individuals who embrace radical elements of the anarchist, animal rights, or environmental movements and are often willing to violate the law to achieve their objectives.DHS worries that the lefties will engage in cyber attacks. Presumably the left are smarter and understand that internet thing while the right are too busy building shelters in the middle of Wyoming. They also worry a bit about real-world attacks by the animal rights folks - perhaps sensibly so.
Aren't we all potential threats?
Update: Roissy provides a wonderful satire on Reuters reporting on the DHS report. Follow the first link with caution, as Tyler warns that Roissy is evil.