OK, what sort of terrorist is going to go into a book store and use a credit or debit card to pay for books on bomb building and the like? If a person pays cash for a book, they leave no paper trail. This is one of the stupidest things I've ever heard and a waste of the taxpayers' money.
Not to mention, how many college kids are going to end up being investigated because part of their history course requires them to read The Communist Manifesto and other such literature? How many disenfranchised HS kids who buy The Anarchist's Cookbook, which is completely outdated and contained all sorts of erroneous information that could get a person killed are going to be taken in for questioning? How many grade school kids are going to be the embarrassment of the neighborhood because they're doing a Social Studies report on the Middle East and they check books out of their local library?
I doubt they're going to nab one terrorist this way. If they do, I will eat that statement, but I think it's a joke.