Isn't his maternal grandmother a Russian Grand Duchess?
His mother was born Princess Marina of Greece. Her mother was Grand Duchess Elena of Russia. She was the daughter of Grand Duke Vladimir & Grand Duchess Maria Pavlovna ("Miechen"). Vladimir was a son of Alexander II. His mother's father was also a son of a Russian grand duchess (Olga, who was married to King George of Greece).
Not only does Michael look like Tsar Nicholas II, but Nicholas looked very similar to his cousin King George V of England. Their mothers, Alexandra and Dagmar/Marie, were sisters. Michael has two great-grandparents that were sibling as Alexandra is his great-grandmother through his father's line, and her brother (King George of Greece) is his great-grandfather through his mother's line.