Or the Canadian team having a banner saying "All of Canada except Vancouver Island and Newfoundland because they are not part of the main land mass"

Or New Zealand's Banner saying "North Island of New Zealand"

Or Australia's saying "Australia: Not so fast Tasmania, just the continent!"

As you said, "Great Briton" is just the name of one island.

If this name is correct at the UN why not be as inclusive at the Olympics?