If the seller says "ships to Liberia only" and you bid on it from Iceland, the Ebay system doesn't stop you from bidding. If you are the "winner" then your winning on it when it isn't for sale to you is treated like backing out of any winning bid, ie it's frowned on mightily.
When an auction ends there's a listing cost and commission payable to Ebay by the seller and Ebay is aware of rather a lot of ways to cheat them out of this money. Many such ways involve delisting items and backing out of deals, so Ebay leans pretty hard on anyone who does those things.