Aviation security is 90% show anyway, most of what they do is a complete waste of time but looks good for those who worry about these things.
I agree, however, in this case the following comment applies
"But if telling the cop you were just speeding to see if he would catch you and let you off works for you graeme, then run with it."
All these stupid antics do is help justify the need for security. The perpetrators need to be given the maximum fine to deter any other d**k heads out there.