Hunter,

From what we know at this time, it certainly does appear that this guy was driven by the very same beliefs and rages that animate the average Islamist bus bomber in Kabul. Yeah, it's just fine to call this guy an "Islamic terrorist." He probably considers himself one (or rather, a "jihadist").

But what the Army will call it has to do with the utility of labels. If it helps the Army to call this guy a "terrorist," the military will call him that. If it helps the military to call him "insane" and "a lone wacko" they will use that label.

Some times a strategic decision to not try to elevate an act to anything like a political/religious act of war, but rather denigrate it as the gruesome act of an insane animal.