Remember all this before you fail to file FP's and GAR's correctly with all the details that are required, remember that it's the accuracy of such administration that allows the powers that be to do their job discreetly and without bother to us all.
I thought your post a reasonable comment unitl you said this.
VFR FPs have nothing to do with the prevention of terrorism. GAR reports are concerned amoung other issues with monitoring the pattern and frequency of traffic movement but provide no protection at all against a light aircraft being used in the way envisaged by the original poster.
As I commented earlier you need to understand that aircraft present a different threat to other conventional means of delivering a weapon. The real concern is an air born weapon which could cause wide spread "damage".
As always we need to weigh in the balance the loss of liberty against the effectiveness of any legislation introduced to curtail this risk.
I am not convinced in that balancing act it is sufficient to claim that there is no historical evidence to suggest x or y necessarily passes muster, in the way that was used in the recent debate of the detention of terrorists. However it is vitally important to demonstrate that any measures introduced will, beyond reasonable doubt, reduce the risk.