A student with a backpack (and door room) full of explosives blows himself up outside a packed stadium and we're supposed to believe the FBI that this was not terrorism. I guess it is all in the definition of 'what is is'. I guess the FBI can claim it was not terrorism because the student, thankfully, only managed to blow himself up and not injure or kill anyone else.
Congratulations! You win a copy of the book 1984, so that you may continue your linguistic education (/sarcasm - actually you win nothing as you understand things well enough)