The Hastings News (Hastings-on-Hudson New York) 19 Sep. 1940 - "John S. Bach, formerly of Broadway, has written to friends here that he is now a flying officer in the Royal Canadian Air Force stationed at Trenton, Ontario. For several years, he has been living in Toronto where he represents an American firm doing business with steel plants in Canada." I guess that may be the reason that he doesn't seem to be in the 1940 US census.
There is another article from the Hastings News from 1934 or 1935 that said Mr. & Mrs. John Edwin Bach spent the week with his mother. The couple had been living in Cleveland, Ohio for a year and had left for Hamilton, Ontario, where Mr. Bach will represent the Ferro Enamel Company of Cleveland.