Going by the FBI's history, the kid likely suffers from some kind of mental issue and the FBI were every other person in the chat room convincing him to attack while providing explosives.
[1] TL;DR if a member of the Inner Party asks if you are willing to kill innocents and throw acid in children's faces, please don't say "yes".
They have learned to entrap people without legally being considered entrapment. Not what I'd consider a good skill for them to have.