I'm kinda on the fence here. Torching a few SUVs, while reckless and irresponsible, does not include the willful harm of humans. His intent was to destroy the property, not hurt anyone. As such, I don't like that his sentence is greater than that for crimes where the intent WAS bodily harm (eg murder, rape, etc). Then again, he deserves punishment, and as for the case that the sentence will ruin his life, well, nobody forced him to burn the SUV. He fucked up, it's his fault.
As for classifying him as a terrorist, here's a definition:
Hmmm....