Reminds me of my boys who always wanted to visit the FD of the LTU L-1011s we often flew on. The Captains were obviously sufficiently impressed with their interest and behaviour and were never in a hurry to kick them out. Generally, with two spare seats on the FD, myself and one of the boys were invited to stay for the landing. However, on at least a couple of occasions dad was sent back to the cabin and my two young sons (13 and 15 by then) were invited to stay for the landing! We never crashed! But even in those "good old days" it was always the captain's decision. So those who were not keen in admitting passengers to the FD were not obliged to. Even LTU had the odd captain who refused having anyone, even company staff. It was their prerogative and nobody thought otherwise.