You don't have to be on a terrorist watchlist to be a radical. The perpetrator was Muslim, American born, at that. This level of violence and depravity wouldn't just come from any bigot, the situation reeks of religious zealotry and salafism.
Well of course, but this guy's parents said it was probably due to the fact he saw a gay couple kissing. Regardless, if the Islamic religion is to survive or move away from this extremism,reformation is very badly needed.