Joining and locking down the account by disabling all the notifications would make them stop spamming you. Dunno what's more important to you, getting rid of the spam, or the principle of not having an account there?
Sounds to me like the "spam" you are complaining about is a communications service for your friends. No lawsuit there, unless every email you get from your friends but didn't ask for is also considered spam.
Would an invite to gmail by a friend be considered spam?
Nor is this "data scrapping[sic]" you mention anything of the sort if your friends deliberately requested, or passively acquiesced, to Facebook reading their address books.
