Undermining authority means that you do or say things that would make marines lose faith and or trust in the commanding officer and potentially refuse to follow orders thus compromising the chain of command. Questioning them and their ability to make a solid plan or that “he doesn’t know what he’s talking about”, a major, supposedly having graduated officers academy is also undermining authority. According to the rules that is very much a valid reason to BE someone. As for that goober that he threatened, you can ask him but I think it was for disruptive behaviour rather than because he is a “lunatic dictator”.