Notes: While the story of George winning a USN wrestling championship make sense, I haven't seen any documentation of that event. He does seem to have had a notable lack of trouble maintaining order on his command, however.
The account of his death is accurate, as far as I can tell. The bit about sinking a German submarine is embellished. His chaser was engaged in an attack on 24 October 1918 that may well have resulted in a kill, but there isn't any clear evidence, and there may never be. The waters in that area are extremely deep, and the records of locations during attacks are rough-and-ready. There is no report of another vessel securing a sunken U-boat the next day.
Lt. Dole did in fact sail to Russia, as commander of a three-chaser unit; and he served in the North Sea minesweeping division.
Article on George S. Dole, Milton Graduates Bulletin, 1928