Well, contrary to what some people are saying is a 'desperate move' by Sony, I think they did this to be the 'good guy', especially for the press.
For example, since they sent out a legitimate, fair warning telling people "We can and WILL ban you, so unless you stop pirating and stuff, we're going after you. We're giving you a second chance." that seems a lot more of the good guy than Microsoft's move of suddenly blocking thousands of piraters without a public warning.
Sure everyone also supported Microsoft's move, but at least Sony's doing the "second chance" routine, and giving the foolish ones a chance to reconcile and go back to the way of legality.
"Being single is easier on the gaming life, and the wallet."








