As I recall the Lockabie relitive wasn't prosecuted. Procecution would have looked vindictive and not really been in the public interest. I think the same excuse goes for the press when they do thier smuggling attempts. Although taking a green plastic toy gun through BAA security isn't really an offence in any event. The idea being to show that something that looks like a gun can get through security.
As far as the UK is concerned, I can't comment on the rest of the world, the person asking another to take something through security doesn't commit an offence. Odd I know, but I went through this at Heathrow some 10 years ago, after getting out the Aviation Security Act and the newer Aviation and Maratime Security Acts niether myself or my inspector could find any offence we could charge someone with after a similar incident. Of course the person taking a package through, if he doesn't admit the package isn't his at the security questions stage does commit an offence.