How do you tactfully and respectfully refuse an unlawful order without getting in trouble?

So.. you PFC O'Mally's 1st Article 15 had a visit from the 1SG prior to being read part 1. The visit went something like this:
Private, what you said was right. What you did absolutely needed to be done. That NCO is out of control and needed to be put in his place. But.... You don't have the rank to do that, and you were absolutely wrong to disrespect him like that. Tomorrow, you will be in my office at 1700 on the dot to receive your Article 15, do you understand?

You can be right, and still be wrong.

After the buttchewing which I hope you took with dignity and professionalism, print out the excerpt from the regulation and show it to your NCOIC.
Perhaps phrase it in the form of a question.
One other thing, if they can see your socks, you might not be in a correctly worn uniform anyway

Site paragraph and line. And make sure to use all of your military customs and courtesies. Through in a couple witnesses, the higher the rank the better.

In the military whoever has the higher rank wins the confrontation. We have to choose our fights. Small things are not worth a counseling statement.

Both CSM Richard StCyr and MSG Thomas Gould nailed it with their comments.

The best leaders know when to pick and choose their battles.

Your use of the word unlawful was not incorrect. But my first thought was along the lines of "Go shoot those civilians." And my knee jerk reaction was you put your weapon on the person issuing the order and take them into custody. My guess is that would not fly over socks.

A lot of times an AR 670-1 Nazi will tweak the reg for the sake of uniformity. Sounds like this might be the case. Me thinks you might have stepped on your crank big time.

I personally would have rogered and kept it moving. If I had a pair of socks to change into I would do so because its not hurting them or me and I ma doing what they want in the end. I would make sure I communicated the incident to my first line leader so there is no misunderstanding. At that point I know that and first line leader would be competent enough to fix the misunderstanding of the regulation with the higher ranking NCO. Even if that means me bringing the reg to my first line leader for them to bring the higher NCO, if neccessary. If the NCO hasn't said anything to you since the incident they may have brought it up to someone and was corrected about the regulation. The last thing you want is your "Speaking up" to be misinterpreted as being disrespectful. Just "Roger" through it. Dont make your work environment hostile on your own. Some things dont even need to go that far.

Let me correct myself and change a word in my question. Instead of unlawful I would like to say it was unwarranted. That’ll change the dynamics of my question and allow anybody who reads this to understand my position a bit more.