Interpretation of the law, and what is taught in seminars as doctrine, isn't always the law. Heck, the Supreme Court interprets laws differently all the time.I guess the U.S. Army lied to me for many years. Is the above what they told you in all of the International Humanitarian Law and Law of War training you attended? I also never once laid eyes on a bullet that wasn't an FMJ.
As a lawyer, I can say there is NEVER an easy answer when... its why people hate lawyers of course. So when "its only FMJ" is the policy interpretation, but it doesn't say FMJ in the actual "law", that is what level the people teaching knew of or wanted to repeat.
Its why some went back to what it actually said, rather than just repeating the same thing.