"He tried to beat up an old man in a restaurant"? Really? When was that? Because the closest I know of was the David Irving incident, where he protested the speaking event of a holocaust denier at a restaurant, and one person in the group (not Hammond) accidentally hit an unrelated patron with a bottle. They never tried to "beat up" anyone. And "he's threatened many people with physical harm"? Again, where are you getting these ridiculous statements from?
Your claim that he's "been to prison multiple times" is particularly laughable. He's been arrested multiple times. So had Martin Luther King Jr. and pretty much every civil rights activist I know of, along with plenty of the anti-war protesters in the 2000s, Occupy protesters in the 2010s, and hell, members of congress and mayors I know of. Are they all "terrorists"? Hammond has only been to prison for the hacking charges. Not every arrest means you land in prison, and assuming that it does is insanely presumptuous.
"And he's involved with the hacking and leaking of private and public information, basically to cause damage to the federal government, capitalistic entities and individuals." He leaked information he thought should be public. It was illegal, and a lot of people (most?) agree that it should be. But how was this significantly different than blacks doing illegal sit-ins at segregated restaurants during the civil rights movement, other than the former offending your personal values this time? Just because something is criminal and political doesn't make it "terrorism," as much as law enforcement and prosecutors would like you to believe otherwise.
[correction: He's actually been to prison once before this, for another hacking incident.]