This could be part of a squeeze play to get him talking. Just a thought, I haven't followed all of the intricate details.
I had the thought also. We all heard the reports of the scheduled sentencing. It seemed he had a pretty straight-forward deal struck. The delay suggested to me there was something wrong with the plea bargain, either in his willingness to cooperate or with the discovery that he had misrepresented something. Or, maybe the judge needed some time off for the summer.
Or maybe the judge is locked in a closet in a certain house in Chappaqua!;)