That’s a bullshit analogy. In your scenario, the drinking compromises the pilot’s ability and competence. Taking a picture with a dead terrorist doesn’t compromise a SEAL’s ability or competence to perform his mission.
What's the underlying reason for regulations prohibiting what he did?
Alcohol has a clear and measurable detriment to anyone's skills, and judgement. Using it on duty even without getting in the air would destroy trust in a pilot or member of a flight crew to perform their duties safely and bring into question what other times does this person ignore the rules?
Similarly, what effect does breaking an established rule have on the perception of Gallaghers judgement and his superiors trust in him? Sure it doesn't make him any less able to kill, but it does cast doubt on his ability to carry out a mission to the best results including how the world sees it when the dust settles or what other rules might be conveniently forgotten when it suits him.
I recall being told once that we aren't paid for our skills, were paid for our judgement. I bet that applies to the NSW community too
Missions that the white SOF community often preform aren’t always direct actions where they are kicking the door down and shooting people in the face. HAL’s ignorance of SOF is showing because he doesn’t even know what missions SOCOM preforms. Depending on the area it’s most likely some sort of FID, IW, CA, or other stability op. Clearly a lot of those missions involved working with indigenous personnel. So yes, posing with a dead corpse that may or may not be a part of the community would absolutely call into question his judgment to preform some of these mission sets.
POTUS made his decision, and that’s about all that’s left to be discussed. I would bet the President is not winning a lot of friends in the Pentagon over the last year or two.