It's kind of ironic.. How does one of the most wealthy persons on the planet and arguably the most powerful man in technology protect himself from hackers or spies. Turns out a piece of duct tape works just fine for Mark Zuckerberg.
Just like any service, Facebook has a certain amount inactive accounts. It can be that the owner has died, lost interest or it's a spam account that's no longer used. Facebook is now having a spring clean where they will be removing inactive users from Pages' like count.