The librarian, Daphne Aldershot, would have to be desperately lonely to accept a date with a man all evidence points to being a stalker.  (On the other hand, people with self-esteem that low do exist and are more common than one would think.)  In real life, safety regulations are not construed as requiring 100% proof that no accident will occur.  Planes fly every with minor protocol violations.  If the chance of a mountain collapse are lower than that, say, of a freak earthquake or a plane crash, I imagine that it would be ruled safe enough to use.  Thriller, premonitions.