Law enforcement listened to music Sullivan had posted online. They found lyrics about killing the president, bombing the senate, killing his grandmother, racist lyrics about killing people and bombing churches, killing and raping children, shooting up a school and bombing a specific public event, according to a probable cause statement filed by a prosecutor.
Sullivan told police he was rapping as a humorous fictional character when he made the videos. He said he doesn’t actually want to rape or kill anyone and doesn’t own any weapons.
Upon re-reading, the threat to bomb a specific public event was most likely where the line was formally crossed. IANAL