People are misundersting what honour is. It's not about dying the right way, it's about living the right way.
Slyvannas is all about getting the job done, the best way for her people. War is a lot easier when you don't have to worry about morals and committing dubious/evil acts. That's what Saurfang objects to.
There's nothing wrong with deciding that Slyvannas is right. Just don't try to claim the moral high ground at the same time.