An interesting post, sky9, which raises some equally interesting points, IMHO.
The Eye article is incomplete, and therefore perhaps unfair, as it does not identify the carrier by which the "in-transit" journalist arrived at LHR. Even if it were BA, the first point that emerges is that LHR security discovered the offending item, and therefore would be deserving of praise rather than the criticism implied in the piece.
It does not specify which item of his "luggage" contained the launcher. I find it almost unimaginable that it would have been in his hand luggage out of anywhere these days ---- even the Gulf! It must surely have been in his checked baggage and therefore top marks to LHR security for such thorough screening of transit bags (a source of previous bomb tragedies).
Following the above assumption, the launcher would not have been available to him in flight and therefore did not constitute an immediate security threat. As he was not trying to smuggle it into the UK - which would have indeed been a criminal act - no charges were pressed, although I tend to sympathise with Faire d'income's comment re nationality. Whether or not US Customs in Washington take a more liberal view on "personal" RPG launchers than do we Brits is another matter! It found its way "on to British soil," but it did not find its way out.
Interestingly, the article immediately above the one referred to concerned the much-publicised looting of the Iraqi Museum in Baghdad. This item ends, ". . . .when customs officers in the US recovered 12 stolen Iraqi paintings. They were found in the luggage of Benjamin Johnson, an employee of the Times's sister company, Fox News Network, as he returned from covering the war in Iraq."
I feel sure that both these incidents were in the interest of the highest moral standards of investigative journalism and that, once the facts are revealed, we will see that they were upholding the finest traditions of their profession. "Shurely shome mishtake?" as they sometimes say in Private Eye.