I don't think the range of the shot is in question here. if it is, then I think it is up to the shooter to decide what is ethical and or manageable. I have seen videos of clean shots taken at ranges of 1000 yds and more and these animals dropped on impact.
examples Wyoming Elk at 1000 Yards Kill Shot - YouTube 1602 yard shot 338 edge - YouTube Long Range Hunting. 1100 Yard bull moose kill - YouTube
Now if were talking about shooting an animal facing you as this one surly was then I agree there is questionable ethics involved.