We just released a great Addon which will simplify your needs to block any country to your Geo installation:

Block Countries Addon from Interactive Villages

If you have scammers poaching your Geodesic site, BLOCK THEM with the Block Countries Addon! The Interactive Villages Block Countries Addon allows the site admin to block access to thier Geodesic site by country or IP. The control panel allows selection of individual countries and the admin can set the allow/deny for the selected countries in the Addon Control panel. The site administrator can choose to use a 404, 403 error, or a 301 redirect, or a custom message and or redirection based on configuration choices. You can forward them to any place you choose. Every single country in the world is in this database.

This Addon includes the IP2Country addon listed below, so the admin can publish the visitor IP and country flag on any page for those countries which are allowed access.

Browse to http://www.geodesicaddons.com for more info or to purchase.