I've read a lot of posts on this subject regarding the fact that the comment was a 'joke'. My point being is at the time how does the security guy know that it's a 'joke' the moment it's said?. From his point (as I understand the story) he finds a penknife in the police officers bag, the next thing the person in front of him, who he doesn't know from Adam, says something to the affect that 'careful you might find my gun'. Confronted with that kind of statement at anytime, not just post the events of the 11th of September he has to take it seriously. As for wether the comment was made as the result of a question, thus constituting an offence, it's conceivable that the security guy asked him something along the lines of 'is there anything else I might find in your bag?'. If the 'I've got a gun comment' was made as a result of that sort of question then I would contend that an offence has been commited. Also just because the officer produced a warrant card to somehow justify his comments is irrelevant as again at the time the comment was made the security guy didn't know (or shouldn't care) that the persons bag he was searching is/was a police officer. Also it's not unknown for hijackers to use fake documents, so why not a fake warrant card. Taking all things into account I feel the security guy acted correctly in refusing to allow the passenger to proceed until the facts could be verified.