Because this anecdote about a herd of barren-ground caribou is not central to the theme of the story, which is woodland caribou; as urgent as may be your apparent need to emphasize the alleged ill deeds of this one group of indigenous people that one time. 

I do not think a campaign of distraction and division like this will succeed when anyone can get a glimpse of the truth by firing up google earth. The time-series of images it now offers, dating back the 1980s, makes the situation clear to anyone who is not paid to misunderstand it.