Is this the sickest joke in the Great Olympic Farce?

I think that this is the most serious con trick being played on the public which is saying quite a lot considering the extent to which we have been misled and deceived throughout the whole sorry business of the Great Olympic Farce.
London is now surrounded by a ring of air defences, air to air missiles and fast jet fighters which are supposed to stop airborne terrorist attacks on the capital. How exactly?
Apparently, if an airliner is hijacked and is identified as a threat to London, David Cameron is empowered to give permission to the military to shoot it down.
This doesn't make much sense because an airliner shot down randomly over London is going to cause as much damage and as many deaths as if it had reached its intended target. Plus, the terrorists would be just as martyred and would find their 72 houris, or whatever rubbish they it is that they are told, waiting for them at the gates of paradise. So in that sense it isn't even a deterrent let alone an effective form of defence.
In any case I cannot imagine Cameron summoning up the nerve to have a plane shot down when it might kill a large number of voters in the process. It's all just another piece of Olympic deception.