You're arguing that Joseph isn't a hero because of the actions of the rebels. That makes no sense.
Riddle me this: Which of the endings imply that Joseph isn't a hero? The last lines of both implicitly state that he is a hero, regardless of the reader's interpretation of the story.
[You spit on mercy? Then you will have none! You want carnage?!]
[Garrosh will get more blood than EVER he bargained for!]