Fair enough argument I suppose but let's be honest. When the US names and charges a North Korean hacker it is more of a badge of honor than a punishment. I would expect that "PJH" or any other government hacker has and will receive special treatment from N.K. leaders now that the US has charged him thus proving their skill and value to the state.
While not directly related to this case, the following wikipedia entry has a fairly good explanation and view points on a "just following orders" style defense.
Do note that most of this article focuses specifically on unlawful orders. Nation state hackers are not committing war crimes, so Nuremberg references are irrelevant.