IIRC, it was reported somewhere (I don't have a link at the moment) that the property was vacant at the time. I believe it was reported that it was used as seasonal residence during the summer months.
Many people in Blairmore work out of town during the week. Many properties are unoccupied for extended periods. Even Randall Hopley knew this. Heck, he changed the locks and refurnished the place before he was found.
http://www.ctvnews.ca/mobile/record-shows-hopley-was-a-skillful-cabin-squatter-1.697663