Unless they're current ATC or current airline, I would say they have no business on the flight deck of a commercial passenger flight. Not in this day and age
Probably true in todays terrorist fearing climate, but a pity, a great pity. A pity that kids or genuine enthusiasts, can never experience the thrill and excitment of a once in a life time visit to the FD, even for a few minutes, to ask a few questions and gaze in awe, like in the old days. Of course, this also applies to the veiwing areas at the major airports. I still remember the Queens building at LHR. I think it was wrong to close those off as well.