Come now. If someone says "I have a bomb in my luggage" (as a joke), that's hardly "on any suspicion". The person has spoken what amounts to a possibly serious,

Come now. If someone says "I have a bomb in my luggage" (as a joke), that's hardly "on any suspicion". The person has spoken what amounts to a possibly serious, realistic threat, and the security person has literally no other means of determining whether it was a joke or not.