>If you're worried about this, perhaps you should also be worried about entering the US -- including in transit -- in case you are declared to be an unperson and sent to Gitmo with no trial or legal recourse.

Quite.

>It's a bit worse than a maximum of nine hours of pointless tedium and handing over your Gmail/Facebook passwords which -- let's face it -- the spooks will have if they want them anyway.

I think you missed my point. Asserting your right to silence is a crime in this situation. You can be further detained, charged, prosecuted, jailed and/or fined for asserting a basic right.