Patriot, or terrorist?

Both.

He held an honest belief, albeit wrongly, that he was taking the best course of action for the greater good - with the exception of the attempted murders of his family, which I think are being overlooked here. He was standing up for what he believed in.

Patriot.

His method was to try and kill, maim and destroy, preferably spectacularly, in a manner designed to shock onlookers. His aim was to bring fear to the authorities.

Terrorist.

By the way, the US may well have a legal definition of terrorism. It's that sort of place. That may be more or less restrictive than the dictionary definition. If so, the government would be correct to say that it was not an act of terrorism, provided that was the definition they were referring to.