in the polish incident, flight deck acccess was irrelevant. the pm insisted that the aircraft land. he could do that from his seat. and the captain could refuse the pm's order to land even if the pm was in the flight deck.
i think we have learned a lot about how good training is and how good it is not. many accidents have occured due to poorly trained crews but that does not mean that in certain circumstances visitors cannot be permitted to the flight deck. blind adherance to rules has not proved to be an effective preventer of accidents.
i am all for situational awareness and common sense in the wider sense of the meanings and for smart skips to decide. those folks who adhere t the rules for the sake of the rules will be undone more often than those who know when the rules do not apply in a certain situation.
i would rather know that the person in the front left hand seat is situationally aware and blessed with common sense than with an intimate knowledge of the rules minutae.
i still think flying is more an art than a science althogh of course a high degree of scientific awareness is essential!