Of course those guys fit the definition of "terrorism," Ski-be.
I've had this argument before, and i've decided that the semantics aren't all that important to me. "Terrorism" has such a stigma because of how muslims were (unfairly) viewed post 9-11. Now, in response, SJWs want to call everyone who commits mass violence a terrorist.
Whatever. If people want to call this guy a terrorist, let them. He's not (assuming he had no motive), but it's definitely not my hill to die on. Maybe in the future we'll just start saying "political terrorist" to replace what "terrorist" used to mean. The world will keep spinning.
Anyway, in my view "senseless violence" as distinguished from "terrorism" is worse. I can at least conceptualize the idea behind terrorism. I cannot imagine how someone could just want to go out and commit violence for no real reason.