JMC were absolutely right in what they did. Security applies to everyone, regardless of age, sex, race, skin colour. Those of us who work for airlines/handling agents/airport security have no tolerance for this kind of "sick humour". By denying boarding to those people who think it is funny to make jokes about security we will eventually get the message home. You want to mess with me at the airport and I will mess with you. I will go home at the end of the shift with a pat on the back from my employer. You will go home with your holiday ruined.
As an aside (and no doubt I will be slated for this) the youth of today have little respect for authority, and are often rude and arrogant. A good slap down like this is what so many of them need and in the future the individual concerned will thank JMC for what they did - it will have taught a valuable lesson to him about respect for authority and the law. Remember compliance with security questions is the law.