Hemingway was a journalist for several publications, including the Kansas City Star, the Toronto Star, and the Chicago Tribune, but there's no record of him working for the Moose Jaw Times Herald. He lived in Kansas City for a short time, but his journalistic career focused on larger American cities.
It's possible that he may have passed through Moose Jaw on a trip, but there's no evidence of a connection between Hemingway and the Moose Jaw Times Herald.