Call it what you want. Disgruntled citizen. Angry anti-governmentalist. Stressed out taxpayer.
It's terrorism. Flying a plane into an office building where hundreds of Americans are working with the intention of committing suicide and taking out federal employees is terrorism.
It's not "Islamofascism." It wasn't done by a Muslim. It was a pissed-off white guy furious with the government.
But it's still terrorism.
If he survived, do you think for one nanosecond the right wing would demand he not be read his rights and be tried in a military tribunal as an enemy combatant?
UPDATE: He had two terror targets. The building and his home where, it turns out, his wife and daughter were in at the time he set it on fire.