What I don't understand is why this is a security breach (if quotes are accurate). If I am travelling with (say) a firearms duty I would be very reasonable to ask if any firearms were in his or her baggage. Also, he was repeating a question the check-in staff asked of him!
And yes passengers do think they are funny, they and the other 74 that week believe they are the first to make any joke to staff. Have you ever (tried) to make a joke of something to an employee in another industry...they've heard it before too.