This thread has so far been about terrorists. I would hope the very expensive spooks and the masses of intrusive data gathering / CCTVs that invade our lives will pick these guys up well before they get in a helicopter. Hopefully every MI5 agent has the intelligence to realise if a suspect is taking helicopter lessons there may be a risk.
Surely the much greater risk is a rated pilot who develops mental illness, or a grudge, or simply gets depression and decides to go out with a bang. And I just cant see what is to stop that person filing his flightplan in advance, even assuming he wanted to commit his atrocity without breaching these regulations.
Or indeed what is to stop the terrorist or pilot with bipolar disease doing his dastardly deed the day before the regulations come into force. So why do we have this shut down, which is unjustified and lacking any benefit at any time, for so long?