How about giving points for self defense? Like, if it can be scripted, don't give scores if the civilians attack the victim first. Instead give score if the other class guy attacks the civilian first.
Let's assume a civilian is just driving or flying (esp. Air) normally. Just going here and there and driving around the city and pming his/her friends. Then a security/cop/terrorist comes out of somewhere and shoots the civilian. The civilian successfully manages to kill the attacker. Then, give like "Self-Defense Bonus:+2" maybe?