Maybe it's my unenlightened American perspective coming out here, but why is this a big deal? You chose to use the Facebook service, you chose to provide this information to them, and you chose to agree to their terms of service. Facebook isn't a government agency, it's a private organization that has persuaded people to give it armloads of data about themselves, and uses that for whatever completely legal purposes i…
Under US contract law, misrepresentation is sufficient cause to rescind an otherwise binding contract. The contract users enter into with Facebook is to accept their terms of service in exchange for being provided with a certain service. If the user can make a case that the service was misadvertised, e.g. by promising a "delete poke" functionality that was not, in fact, provided as expected, then this can be construed as a breach of contract on Facebook's part.