SIMPLE QUESTION
IF you really know things, some foreign (not USA) carriers DO allow visitors to the cockpit in flight.
DOES anyone really KNOW The MALAYSIAN rules regarding cockpit visitors and smoking?
And to tell you the truth, if USA airlines allowed visitors to the cockpit, I would authorize it as captain. When I was 8 years old (prehistory) I rode in the cockpit of a convair 240 airliner (UAL) and loved it. And the guys didn't mind me being there.
SO, if someone actually KNOWS, please let us KNOW.