Many civilians are unaware of what an MOS is, and for those unaware an MOS is what is called a Military Occupational Specialty and many are and can be non-combative roles like working a desk job as a clerk filing paperwork. In instances of your MOS involving intelligence gathering IE Humint, Sigint ETC you won’t always be authorized to carry your service weapon let alone use it, so not all solider have an MOS that involves killing the enemy even if on the front lines. A solider being asked if they’ve killed anyone is rude because of it’s ignorance, and the arrogance of not wanting to show respect only solidifies that.