Warren Buffett may be most famous for the billions of dollars he has made from investing but he is also well known as a cheerleader for the United States. The Oracle of Omaha routinely exhorts investors to put their money in America, “the mother lode of opportunity,” as he wrote in his annual letter this year. So Buffett’s participation in fast-food chain Burger King Worldwide Inc’s purchase of coffee and doughnut chain Tim Hortons Inc – complete with relocation of Burger King’s domicile to Canada – might at first blush raise questions about his patriotism.