How about the following scenario?
Let's suppose that, instead of being arrested, the liquid bomber terrorist suspects had made it on to their target airliners. The same thing happens as on the Monarch flight - some passengers become concerned at their appearance and behaviour and decide to leave the aircraft. The Captain is alerted and decides to investigate . . . Reviewing ALL the circumstances he considers the wrath of the politically correct establishment. As the dodgy looking passengers have 'passed' security he can see no objective reason for their removal. He dares not make a subjective decision for fear of being prosecuted for racism and being chucked out the industry and losing his home because he cannot afford the mortgage.
So, the aircraft takes off. In flight the terrorists successfully launch their deadly attack.
As I recall, Richard Reid was treated with suspicion but allowed to fly based on objective evidence.
I saw the two young men interviewed last night. They seemed to understand the unforunate nature of the situation and bore no grudge.
My point is this. We must not introduce new protocols and strictures to ensure politically corrrect outcomes in all situations. We pay the Captain to make subjective judgements in the interests of safety. When there is insuffcient information we must respect a decision that errs on the safe side.