Did they not get this name because they supported the Hanovers (King George) rather than the Stuarts? There is also an Archie Fisher song, or a song he covers, which mentions "German Geordie."

If I am not mistaken, "Geordie" is also a common nickname for "George" in northern England and in Scotland. My paternal grandparents were from Lancashire, and the family always called, and still call, my uncle George "Geordie".