I only found it by accident due to my curious nature And one can only do it through the forums. When you log into the selling side of things you only see what is available to the country site you are logging in on.
Have you heard from support about how they would handle things if you had a buyer from a country you didn't want to ship to but couldn't omit from the list? The only thing I could find in Seller FAQs was this:
26) Can I stop unwanted users from bidding on my listings?
If you have had a bad experience with a member in the past and you do not wish them to bid on your listings you can enter their name into your 'myBlackball' section of your login. This has the effect of stopping the member from being able to bid on your listings. Hence, the user is 'blackballed'
You can check out "My Blackball" under your "My Ebid" and see what the options are and under reason write "Do not ship to "whatever country".
IMO, it is seller's choice where they want to ship to and if the present system of shipping options doesn't suit your needs, I can't see why the eBid staff would object???