Yeah, this is just caving in to stupid paranoia. Christ, the Washington Monument is even open and allows you to go all the way to the top, and it’s less than a mile from both the White House and the Capitol.
If they’re concerned about numbers, why not do what the Monument does? Send up a group every half-hour, and have a fixed maximum number of people in each group. Give out tickets to people who want to go up, and when all the tickets for a particular time slot have been distributed, then that time slot is deemed to be full.
Last time i went to the Monument, i was taking a friend from Australia. I knew we wouldn’t be able to go up straight away, so we went and got tickets for the earliest possible ascent. Our ticket was for the 3pm group, which gave us a few hours to kill. We went to the National Gallery and had a bit of a look around, and then walked down to check out the Vietnam War Memorial and the Lincoln Memorial. By the time we’d done all this, it was time for us to go up the Monument.
They could do something similar in New York. Distribute the tickets at the downtown wharf. That way, if people have a lot of time to kill, they can go shopping or something before getting the ferry across to the Statue.