Having been through many secondary inspections at the US border (don't ask) I kind of agree with you. Essentially they're doing an interrogation, and they deliberately browbeat you in the hopes that you'll actually reveal something incriminating. Anything that will give them a shred of leverage they will use to try and intimidate you (none of the things in the article are actually incriminating, but they're "leverage").

EDIT (sober second thought): The phone tap (if true) does seem a little beyond the pale.