Well seeing as how the gunsmith is tied to multiplayer, im not sure if CH will make that an option since there is suppose to be a fixed number of unlocks you are allowed to have.
Campaign mode unlocks (all through challenges and progression) and MP mode unlocks are separate. Even if you unlock in campaign mode, it is not unlocked in multiplayer so having a cheat that unlocks in campaign mode wouldn't affect MP.
*edit* oh, to clarify some unlocks such as using characters from the campaign mode in MP mode needs to be unlocked in campaign mode first.
Has anyone found a file with the gunsmith unlocks in? If so could you tell me where in the game's directory it is located please? I'd like to be able to unlock all attachments for SP.