Timothy McVeigh, who killed over 500 people when he blew up the federal building in Oklahoma in 1995 has been labeled a terrorist pretty much since day one, and nobody really denies it. In fact, when someone makes a claim about terrorists being mostly just Muslims, Timothy McVeigh is pretty much the "go-to" guy to show otherwise. IIRC, McVeigh largely acted alone, though he did have some minor assistance from another guy. Seems to me, if you're going to consider McVeigh a terrorist, you're going to have to consider Monis a terrorist as well.