Someone aeons ago gave the advice "stay behind" stay in your house, even if it doesn't have a bunker. The more people killed following this advice, the less motivation for changing the advice (thereby admitting the earlier advice was less than optimal).
Why wouldn't anyone want to admit that earlier advice could be flawed, especially in such a serious matter? I can understand them wanting to preserve the image of infallibility in order to keep people listening to the advice; but if the original advice is less than optimal (i.e. demonstrated to be incorrect by the events of the real world) then there is no point in giving it in the first place.