This is a good piece but I have one nit: it is incorrect to say "thermite [...] will not detonate." I was shocked to discover this first hand some years ago: http://olivernash.org/2009/11/12/fun-with-thermite/index.htm... I can still recall the echoing boom of that (copper) thermite.
I'd stop short of claiming that flour "detonates" or that flour purchases are terrorist indicators...