Wino - Yes the manouvering MAY injure a few, but do you REALLY think these hijackers are not going to do a little more than INJURE the pax to try to pursuade you to open the door!
As far as the aircraft taking the manouvers goes, you only need about a half "G" negative followed by a positive pull and I am sure there are not too many aircraft not capable of that!
As far as "inconvenience" goes, I am more frightened of being trapped in the cockpit after an accident than worried about a little inconvenience (being American how long would it take your relatives to have a lawyer suing because you died for this reason), this I would suggest is going to happen MUCH more often than attempted hijacking.
N.B. please could you get my user name right, or doyou not realise it is an aircraft type.