Although I really don't know how their risk assessment was carried out, I think you raise a good point, Sillert, and I'm certain it will apply to a number of other venues - I've mentioned Farnborough here before. As the urban areas in the UK have expanded, they have encroached on the open areas that used to surround a lot of airfields and airports to the extent that even normal arrivals and departures are flown over houses very close to the thresholds.
I fully agree with your point about risk assessments finding the answer they want, too.