Working on an abused and neglected Argo 8x8 to Make it Great Again is definitely a worthwhile cause. These used Argo 750HDi still typically sell for $13k - $15k.
I couldn't find any references in the service manual or discussion forums about them needing to be loose. There's no reason to allow the rotors to be so loose when the brake pads inside the calipers float. If anything, going off how loose mine were, I would be concerned of excessive wear on the rotor disk spines or the shaft spines. Why would they want the rotors on the Admiral transmission to "float" but not in the Gen 1 or classic transmissions? Is there a binding issue on the steering brakes if the rotors don't have some wiggle to them?