It's funny to think of Clint Eastwood playing any character that is "beyond war." However, in the movie you do see a real transformation, from a man who absolutely cringes at "zipper heads" and threatens/uses violence at every turn, to a man who ultimately gives his life non-violently to help his friends. Furthermore, he actually stops his friend from using violence and killing those who hurt his sister.
However, I would argue that he still does not accurately portray the beyond war principles. The reason he does not live beyond war is because he fails to discourage violence (in fact he provokes it) even at the final scene. While what he did was incredible, he set up a situation for violence. I also think the character (Harry) failed to follow the three practices, most obviously the practice of not preoccupying yourself with an enemy. He did not maintain an attitude of goodwill to those whom he wished harm.
I have to agree with you about how he doesn't quite fit into the beyond war principles. I would say that it would be important to see the movie because of how it integrates some of the bigger principals. I think that in some ways Harry moved his friend away from his first stance which was more beyond war then the way he was at the end of the movie right before the climax. Then again his friend is completely beyond war I think after the movie comes to a close.
PS. New movie to watch which made me think about beyond war.... The War (1994)