By that rationale, a Behemoth should be able to carry 39 Leopards - a suggestion that pops up from time to time. TPTB have ruled this to be impossible but haven't given a detailed explanation why, except game balance.
If you want a detailed reason why not, it's because DropShips carry KF equipment which it uses to deform a KF field and stretch it over itself. You can't carry a DropShip that isn't plugged into a Collar for the same reason you can't jump with a JumpShip. Or why you can't carry a DropShip in a DropShuttle bay.
The Argo....as described...is illegal. Now, much of the limits in the construction rules are arbitrary. There is little reason why DropShips cannot carry a GravDeck or Docking Collar for example. Easy enough to adjust. Use the Quirk Illegal.
Daisychaining the jump field, however, has potential ramifications for the universes background such that it is less easy to ignore.
It would require a rule change and/or new equipment. As this wouldn't be an issue with construction, but usage it would require something a bit more radical than a Quirk.
To fluff it....the Argo carries a system that allows for a greater expansion of the KF field than normal, allowing it to Daisy Chain the KF field.
That is, DropShips docked with the Argo can jump with the Argo even if not attached to the JumpShip.
Disadvantages.
1. Each Docking Collar is more complex than that of a standard Collar and so is more massive and more expensive. Say....100 Tons plus 5% of the maximum DropShip mass carried added to the mass of a standard collar
2. The DropShip mounting the Collar must allocate space for the docked ships. An Argo that wants to carry 2 Leopard class DropShips must allocate almost 4000 Tons to "DropShip cargo".
3. A DropShip that wants to move with docked DropShips attached must also be adapted as a Naval Tug.
4. The Internal Structure of the Mothership must then be increased by 5% to account for lost space, and adaptations made to the DropShips KF equipment
5. If additional DropShips are carried, the mothership will require two DropShip collars...one for itself and one to pr9vide the power and feed for the docked ships. Docking time is trebled because of this additional hoookup.
6. Cost of the entire system is increased as a result.