Contextual filters exclude option missing
The exclude option is a part of the views_handler_argument_numeric handler that comes with views.  If it's not there, it likely means your filter is operating on something other than a numeric argument.  What you have is "Indexed Node: Node ID".  If you create a filter on "Content: Nid" instead then you should see the option.

Also see https://www.drupal.org/node/733686 .