Fair post but ironically the main point you make can now be made in reverse. By publicly wanting to break away from the UK, it could be argued he is now grudgingly representing his fans south of the border.
Well that depends on your views about patriotism, like i said earlier he's not a team representing a country he's an individual who happens to be Scottish, who happen to now still be part of the U.K. As an individual, his fanbase is Global, just as much as someone like Federer who has more support worldwide than from his own country, people who say they support Andy only because he is British are not supporting him, they are supporting the country he represents, and that to me is something i don't understand.
As an example, I wouldn't support Lewis Hamilton because he is from England, i can't stand the guy so to me it's more about the individual. As far as i'm concerned, all the people who have decided he is not worth supporting anymore were not true fans of his, their support for him is based on his nationality.
I remember when Tim Henman was making Wimbledon semi finals etc, but i never followed him throughout the year as him being English wasn't important to me, I would actually go as far to say that when he lost it didn't actually bother me as much as it does when Andy loses.