I find the whole thing profoundly sad and tragic. The massive destruction wreaked, people losing their homes, businesses and belongings, the complete ruin of a historic street and buildings in the heart of Nashville, and this man's violent and public suicide.
I don't know what his background or ideology was, but seemingly he was not a malicious or cruel man to others...until this horrible explosion. Was he lonely, was he affected by the rejection of his gifts of properties, were his dogs his only companions, was he despondent over their loss and something in him switched and snapped to such destruction upon himself, and towards others who were harmed by his action?
I don't know if AT&T was a target. Maybe 2nd St had a particular meaning for him. No one knows the meaning of "Downtown" for him....maybe he had a love for someone back then when Petula Clark was popular, hung out with a woman back then in that part of town?
Maybe the song was meaningless.
Maybe at some point, there will be a letter discovered that outlines his motives, but somehow I doubt it.