If the social network is run scrupulously, and those who own and operate it refuse to sell data to anyone while also taking extreme data security measures, you could probably find a way to have a site that did not violate anyone's privacy (any more than they themselves do by posting personal information on a publicly accessible internet site).
However, if you are going to allow actual human beings to use there is no way you can prevent it from being filled with garbage.
Sad, but true.