I don't agree that the burden of proof is met by a terrorist threat, because the people being searched are not the ones making the threat and therefore have done nothing to bring suspicion upon themselves. The terrorist cannot be allowed to determine the liberty of everyone else. If you are going to say the terrorist threat is 99% then you shut down the train, bus, or ship, and deal with it that way. Joe Citizen does not deserve to have his rights stripped because Joe Terrorist wants to make trouble.
I guess a disagree that my rights are violated in a situation where there is a credible threat on a particular bus and that is the reason for the search.
Sounds like you just want to search the terrorists and leave everyone else alone?
(snicker)
Then why search, just go to where the terrorists live and lock them all up now and all will be well...no need for anymore violation of rights cause from now on we will only search terrorists..