I was under the impression that 'they' paid C5 to appear on BB. After all they are z-listers desperately and quite frankly embarrassingly trying to hang onto what little fame they still have.
When you block a person, they can no longer invite you to a private message or post to your profile wall. Replies and comments they make will be collapsed/hidden by default. Finally, you'll never receive email notifications about content they create or likes they designate for your content.
Note: if you proceed, you will no longer be following .