Assuming a successful AD Role and placement outside of exclusion zone, can a Cadmus use its decoys to be placed in an exclusion zone. The Decoy ability is not listed on the exclusion zone rules. I had a game yesterday where I deviated off the table and had to deploy on my table edge. Then used the decoy ability to reach an objective. In this scenario I was definitely able to do it due to dispersion, but it seams odd that its better to fail a role than to succeed.
Automatic when deployed, placing the two Decoy Markers and the model on the game table, within Coherency of each other. Players must respect the general conditions of the Decoy user's Deployment rules. Since the cadmus Airborne Deployment is restricted, the Decoys are bound by the same rule. Same reason you could not deploy a decoy outside of your deployment on troopers that don't have any sort of deployment skills (such as Helots for example) - - - - - Now the fact that the zone is not used when suffering from a Dispersion would indeed mean that in a exclusion zone mission, failing your roll gives you a chance of getting a more advantageous position.
I do not believe this is actually allowed. Since the decoys have to obey the user's deployment rules, including the rules concerning dispersing off of the table, all decoy markers must be in contact with the table edge (but not necessarily right next to each other).