The incident occurs in a setting that robs it of its moral import

Hi

Could you please tell me what "the incident occurs ...moral import" means in the following lines?

Also, I agree with the first reason that the killer's calm disposition does not fit the (action of murder), so the reader is shocked. But the second reason suggests (I think) that the murder was justified; if so, why should the reader be shocked?

Please shed some light on the bold lines.

Henry’s shooting of the engineer for refusing to help free the car from the mud shocks the reader for two reasons: first, the violent outburst seems at odds with Henry’s coolly detached character; second, the incident occurs in a setting that robs it of its moral import—the complicity of Henry’s fellow soldiers legitimizes the killing. The murder of the engineer seems justifiable because it is an inevitable by-product of the spiraling violence and disorder of the war.

Thanks,

Tom