I think another way Destro has a "Code Of Honor" is that he doesn't try to purposely target innocent civilians. I believe that was the original idea that hasbro had when creating Destro, but it doesn't work out, because in the cartoon and comic book (the Marvel Series) they wanted to shy away from Cobra killing innocent civilians. The Devils Due comic series is grittier and lets you see innocent people getting killed, but it does little to support my theory, because Destro was selling hardward to Wingfield and at least "by Proxy" was responsible for the deaths of innocents.

In my JoeVerse, Cobra Commander is like the crazed terrorist, wanting to unleash massive destruction, but Destro wants it to focus only on the parties it need to.