It is possible that William's name is entered in the census as Onion, it is a common misreading of Union. Otherwise it is possible he had moved from Newport News. He lived there in 1908 at 3.38 38th Street, Newport News; that was the address given for him in the ship's manifest (in Ellis Island records) when a relative came to join him from Scotland. In 1939 my father's ship called at Newport Va., and his diary records that he sent a letter to his uncle William Union from there. It was only my guess that William still lived at Newport News, as it is clese to Norfolk.
If you have another opportunity to check the census, it may help to know that William was born about 1879 in Greenock, Scotland, and was married to Ellen or Helen McKenzie, also born in Scotland.