As social network users, we have all gotten used to accepting less privacy is a necessary evil for social networking sites. When you sign up for new social network service, checking off that terms of use agreement checkbox means that 'yes, I trust you to do the right thing when it comes to sharing my information.' And social networking sites usually take this to mean whatever it makes sense for them. Especially when they are introducing new feature, they would like to interpret it to mean, 'surely you must want to use our new service since you haven't deleted your account'.