In this scene, we see the heroes being used by the government to fight in wars for them, furthering the war mentality. Through the reflections of Dr. Manhattan, the audience is given insight into his morality. He sees the "pointless butchery" but still finds himself continuing to fight and kill. He realizes that this is not what heroes are supposed to do. They are supposed to save lives, not perpetuate killing.
In this final scene of unnecessary destruction, we see Dr. Manhattan diffusing a mob by transporting them to another location. Some of the people during this teleportation have heart attacks in the process. We see Dr.Manhattan's analysis of this situation. While two people died, more people probably would have died in the mob. Through this the hero is seen justifying the killing of these people by saying that more people MAY have died in the process. This begs the question of whether the possibility of more deaths justifies the killing of some. The audience is shown these flaws in morality.