If you really want to be PC, go for the COD OpFor, even the US army calls training sim enemy's OpFor. But truly, its a freaking game. Even in MW2 with the No russia level,there is NEVER any prompt to shoot civillians in the airport, yet when people played the game for the first time, almost all shot them anyway. why? its because we are naturally interested in violence, blood and gore. its a primeval thing, we cant escape it.
Playing as terrorists, the taliban or fucking martian invaders doesn't make me want to go out oand shoot someone, and any time a FPS game has caused someone to go out shooting people, its because they were sick in the head anyway, so it woud have happened sooner or later.
So basically, stop bleating about killing digital people and start finding all the terrorists, rapists, pedofiles, kidnappers, burgulars, thieves and thugs, and locking all them up instead!