On the contrary, I personally see Justin's comments as fairly sound. He gets my vote of confidence and his openness is very refreshing. My criticism is that there is no real science of terrorism that will be conclusive otherwise we would have solved the issue long ago.
Fact is exclusion theory works in understanding why violence occurs. It may be overdressed as the American way, but treating people of opposing religion as rubbish and excluding their issues from your thought processes does have its consequences.
Right wing, establishment, everything is ok by me thinkers don't worry much about the dynamics of exclusion until they themselves are the objects of a fast moving revolutionary machine that swings out of control. People are trying to communicate that the repression they feel deeply is not ok! Even if it is at a marathon!
Their feelings are used by those who know how to motivate people into violence. Such motivators give the terrorists a sense of inclusion within a revolution!