Does it not qualify as 'Munitions of war'?
Launcher with no round in it is a pipe and battery. So long as it doesn't have laser stuff etc in it it is no more hazardous than a DVD player.
If another passenger was found carrying just a round for an RPG launcher you could say it was useless without the launcher and therefore harmless. But if they were together....
I am amazed he wasn't charged with a variety of offences. If he was an Arab it would be a different story. Haven't we seen people arrested for using lipstick on lavatory mirrors?
Imagine the terror if he produced it pretending it was loaded. At the very best this journalist was spectaculary irresponsible!