I'm guessing since Terrorism is a federal offense, and Barney Fife screwed up and got caught well before the act, the FBI/Justice department decided not to bother. Either that, or they couldn't lock Item B down. Based on his comments in the article he may have had no intention of his actions influencing or intimidating others. He almost sounds like his only goal was to kill an abortion doctor.
Which just shows his lack of faith in God I guess.