The Pontifical Secret is more complicated than that. It's the Vatican's way of classifying information. The reason it does that is because it's a state. Most states and governments have a classification system where there are things that are confidential and non-confidential the same way the American, Russian, Canadian governments have a classification system for things confidential. 

In the case of the sexual abuse scandal, Pope John XXIII issued a document crimen sollicitationas which set the stage for the policy in which priests who were a part of a Church tribunal on sex abuse were sworn to secret. The policy was then changed in 2001 by Pope John Paul II. 

All in all I do believe that all the documents around sexual abuse should be declassified so these criminals and pedophiles can be imprisoned. It's just not as simple as people think because classification systems with governments in general are complicated matters. Just look at Edward Snowden and NSA spying.