I am amazed at the complacency in some of these replies. As a pilot for BA I can assure you that we take security and safety seriously. If I were to do what this Spanish Captain did I would be out of a job- yesterday and quite rightly too!
These fanatics will strike at any weak link in order to fulfill their objective and any airline or country ignoring that fact will probably pay for it - big time.
As for the passengers stopping them, if the flightdeck was stormed at the right time eg. on final approach, there would not be time stop them delivering the package, and then it's adios amigos!
ATB, PTC