That's the sort of thing that should have been made clear before the event, or at the very least on the day by a sign at the access stair.
That said, it is not easy to move several hundred people through a plane, even with two access stairs for entry and exit to avoid conflicting traffic. And if each one wants to spend 5 mins taking pics of the flight deck, you have a very big logistics problem - I mean to say, 100 people x 5mins = 500 mins, or eight hours twenty min, and the show is only open 8 hours.
I don't think there were any security concerns, or secret contracts with payware developers - it is just practical management. I can think of a few solutions to improve things, but I wasn't running the show, and in any case I am retired.