This may come as a surprise, but a lot of military contracting is stuff that many people find ethically un-troublesome. Most people within a military contractor are not working on new ways to kill poor brown people a world away or how to spy on a dissident. Plenty are working on how to preserve food better, or how to keep birds away from runways more cheaply or effectively, or how to detect malware. Or monitoring groundwater for contamination.

It could also be worth considering that anyone who makes the choice to work for such an employer has already reached ethical conclusions they are comfortable with.