LOL. I thought the same thing.
I have about ten pounds of it, used primarily for melting old computer hard drives and for entertainment.
There are a lot more dangerous things in the world than thermite though... example, 140 pounds of Uranium ultimately killed about 150,000 people at Hiroshima.
By comparison, 140 pounds of the plant toxin abrin would constitute enough toxin to constitute 280 million fatal airborne doses.
The TSA publishing stuff so that groups like al-Qaida and ISIS can read it is foolish, even if some stuff seems like it should be obvious, because as stupid as TSA seems, those camel-riding morons seem even dumber and not particularly original.
(When I was in high school in the 1980’s when there were air hijackings and the Beirut Marine barracks bombing, I wondered why the terrorists never came up with the idea of hijacking a plane and using it as a suicide weapon. Either I’m really smart or the terrorists are really stupid)