What Is Harvard Afraid Of?

Today was a beautiful, unseasonably warm day, and we went out for a stroll around Cambridge.  When we approached the Harvard Yard, we encountered locked gates and a lot of police.  Even Nick's Harvard student ID was not sufficient to allow me and Nick's two cousins to enter the yard.

Why the lock down?  Apparently, because Occupy Harvard has set up a few tents in front of the John Harvard statue.  For full disclosure, I do not claim to understand their position nor do I want to take a stance on it one way or the other.  However, I would like someone to explain to me how the Occupy Harvard "protest" presents a risk that is so great as to lead the Harvard administration to block people from visiting the historical campus.