A librarian from Princeton University posts this on the archivists' listserv:
Since there has been discussion of this matter, I want to be perfectly clear that Princeton University Archivist, Dan Linke, and I argued strenuously to a number of senior university administrators that closing the Michelle Obama thesis would be a mistake and contrary to archival ethics and Princeton policy, both because it had been open, used and copied prior to the closure, because a resolution of the university faculty in the 1970s said that all materials in the university library open to one researcher must be open to all, and that in fact this would not be in the best interest of the Obama campaign. Nonetheless, the thesis was briefly closed at the request of the Obama campaign. Apparently it didn't take long for the Obama campaign to realize that fact because it soon reversed course and released the thesis to a member of the press who posted it to the Internet, but not bothering to inform the University which in my view was left looking foolish for having closed it however briefly. These of course represent my person view and not those of Princeton University.