Most veterans of any war aren't thrilled to discuss it, and anyone who would brag about killing surrendered troops is an asshole and far, far from the norm of military behavior.
Also, political correctness is a disease, but at the same time the makers of a game are under no obligation to give players the freedom to act, speak, or display images that they feel will hurt their buisness. It's almost certainly all listed in the EURL anyway, if only vaguelly.