Why? No I mean I get personal honor and all that but orcish "honor" already makes room for things like backstabbing, assassination, and myriad other things that the Horde whines about when it's done to them. (The orc cries out in pain as he strikes you.)
Why would she have been cast out as a coward for not letting a 1v1 settle a war that she was poised to win? Are orcs really that dumb?