Hitchens has some great info on MT.
I believe she was involved with some financial fraud. Also she had a belief that pain was an important element to worship and spiritual development. The catholic church as a whole believes this is varying degrees, trials sent to test us etc to opus dei. (Yeah.... Dazza Brown!)
I am sure that many people died under her care due to her beliefs on poverty and suffering. There are ex nun nurses that have left and spoken out.
Why someone would defend such a person I have no idea. Harold Shipman was a good clinical doctor....but a mass murdered. The good does not rub out the bad.