Adding this later on today:
Turns out this whack job was losing his home to the IRS. He torched it (still hearing different stories about whether his family was inside or not at the time) and then jumped in the plane (unclear if it was stolen or his own). He supposedly left a really long suicide note on his website explaining it all. So the building wasn't random, he was aiming at the IRS. What an asshole! If you're going to kill yourself (especially over something as trivial as losing an object!) start with yourself and don't try to take others down with you. Two employees in the building were rushed to burn units. These total strangers will have to live with scars from this guy for the rest of their lives. The family of this guy not only lost their house, but the father and breadwinner. Great solution you selfish douche bag!