It was Yomtov time when the poster publicized going to the Kosel. I think it was Erev Y”K. There were so many people there then – I think my friend even mentioned that her son tried going that day and turned back because it was impossible to get there.
With the whole world there, it’s not really a safety risk. It’s like your telling me that you are going to EY today. There are probably less people on planes flying to EY today than there were at the Kosel that day.