I think Caroline was told she wouldn't be the choice of Governor Patterson to fill the New York Senate Seat left open from Hillary Clinton's confirmation as Secretary of State.
If true, I like the dignity of the process.
Kennedy wasn't prepared to do what it took to be an effective Senator.
That included dealing with different kinds of people in a variety of circumstances, many of them unscripted. Perhaps she could have learned, but more likely Caroline would have tried to float above the process. Anything other than that had the chance for an extreme disaster.
Better withdraw than a disaster in running, or worse yet not being chosen by the Governor.
Patterson should now choose Andrew Cuomo who has done the right thing politically in New York State many times. He has mastered the political correctness game and should now reap his reward.