You're both missing the point.
There are obviously sitations in which you WANT military officers to disobey orders - to not fight when they are told to.
Sort of like the joke:
Guy (to girl): "Would you have sex with me and my buddy for a million dollars?"
Girl: "Million? Hmmm....well, sure"
Guy: "Would you have sex with me and my buddy for $20?"
Girl: "NO! What kind of person do you think I am?!?!"
Guy: "Well, we've already established that, we're just haggling over the price!"
The point being, you agree that in some, extreme cases, it's okay to disobey orders. The question is only how extreme that situation has to be.
Would you want US soldiers running gas chambers?
No, you'd expect the US soldiers in question to consider those orders morally wrong, and disobey them.
If this US soldier things invading Iraq is just as morally wrong, what would you rather have? Would you rather have soldiers following their moral compass? Or soldiers that obey any order whatsoever given to them?
There isn't a middle ground! It's one way or the other. Either your encourage them to follow their conscience regarding their orders, and things like Auschwitz don't happen. Or, you encourage them to follow orders regardless.
Which would you rather have?