There are different standards for bishops.  For example, if I, a lay person, find out someone is abusing a child, I feel it would be morally required to report the abuse, even if no legal duty was involved.  But, bishops, who are anointed by the Holy Spirit to lead the One True Church realize that they can't just do something like this without first considering the risk of causing Scandal to the Church.  They realize the truly moral thing to do is protect the Reputation of the Church, even if it means aiding and abetting abusers.  This approach was endorsed not only by the vatican, but by a Saint and Pope, so obviously it is the Right and Moral approach.  Because they are authorized by God to teach morals, they determine that their actions were moral, and we abide by their teaching.  It all makes perfect sense, when you think about it, and it must, or else we would have to question the basic decency not only of bishops, but of Saint John Paul II, the Great.  And we can't have that.