Well, when you're right, you're right. The doors of a commercial airliner will not open in flight. The FAA mandated that safety feature after the D.B. Cooper afair. The device that prevents the latch mechanism from releasing is automatically controlled by the airspeed indicator and cannot be disabled from inside the aircraft.
This was explained to me in detail by my father, a retired American Airlines pilot - a "self-made" expert, if you will.
There are many things your father didn't tell you . . .
Five bucks says I could get one open.