So, having visa's in his passport which are required to travel, having flash cards and a book critical of US foreign policy are exactly the things I'd expect a student studying US foreign policy to have.

There's no way to become more knowledgeable about a subject than to address issues from both sides, including the negative side.

Should they have addressed why he had all that stuff? Sure.

Did they have to treat him like a terrorist and hold him for so long? Not necessarily.

Did they have to apologize after letting him go? Not required, but if I were doing the interrogating only to find out it's some poor college student scared out of his whits, I'd definitely apologize at the end.

edit: And The Hurt Locker is in the mail to me right now from Netflix, I get it today and am going to watch it tonight.