You asked that yesterday, but the post has been deleted. If you didn’t delete the thread, then support did. If support deleted the thread, then they had a reason for deleting it. If you deleted the thread, then I don’t know if there is a reason.
Nothing has changed. Anyone that cares enough can file a support case, search Google, or for the really smart ones you can click the "Contact" links in both places.
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 .