That does nothing to prevent the app from retaining the information they obtained using the Facebook API during the time they were authorized (yes it's against the TOS to do so, but it's completely unenforceable).
If Facebook had a history of strong privacy protection and strict opt-in policy to information sharing, this wouldn't be so bad. But since Facebook has the completely opposite history, including Zuck coming right out and saying that he would prefer all Facebook user info to be shared, I'm not going to trust Facebook to keep whatever I want private private.