[davesque]

From a scientific point of view, they probably have nothing to apologize for. They did their best to design the system to emulate human behavior (and, it sounds, even tried to restrict this behavior to some level of civility).

However, it's not surprising that they would release a public apology. People will try to blame them for what happened (human nature). It's a good move by them to do their best at damage control. In the court of public opinion, those are the rules of the game.