So where was William in 1910? According to the ship manifest he had already been in the US for 4 years and was employed by and lived with H. E. Aitken at 130 W 57 St, New York. But I don't see him on the census or Aitken, either.
I am guessing that H.E. Aitken was Harry E. Aitken, film producer and distributor, who was listed in a 1915 NY directory. Who knows, maybe William buttled for Mary Pickford and Charlie Chaplin.