Are you in the RNZN? If so i accept your points. If not then your suggestion that there is no room on the OPV for a weapon for the Seasprite is pure speculation. Its not that i dont believe you but i think it would be better to have some hard evidence than to make up observations that dont have proof.
The questions i would have to ask you specifically and without speculation are these:
1-What gives you the idea that there isnt room in the Hanger for a weapon?
2-Why couldnt or wouldnt there be cannisters that could "hold" the Mav. externally? It would seem from the photos that the OPV has room at the rear.
3-If there was space restrictions for a weapon then why couldnt, once the seasprite is rolled out to the launch pad, weapons rolled out from behind the hanger in a room that could house 4-6 Mavs.?
4-Is there evidence to believe that there isnt a room that can house the weapon behind the hanger?
5-Why couldnt the Seasprite be folded up and put inside the hanger with the 2 mavs. still attached? Remember they are not armed.
6-It would appear that the Mav. is more helo "hugging" than many other weapons. So why couldnt the Mav. be still attached to the Seasprite on any given operation.?
7-If many of the worlds Submarine crews are sleeping within close quarters of the torpedo chamber then why couldnt room be made for unarmed Mavs. to be stored within close proximity to the helo in the hanger?
8-To store 4-6 Mavs. then really it would be plausible to argue that the space required to store this weapon wouldnt need to be large. Remember the Mav. is 2.5 meters long and 1 ft wide. So to store say 4 Mavs. wouldnt need much space.
If you have "inside " knowledge that the OPV doesnt have the room well and good, but i would need to see the evidence to make me a believer.
There is no permanent storage (magazine) on the OPV's for any Sea Sprite Launched weapons. I image that they could use the container on the stern for that, but it raises a number of weapons handling issues.
I should add that there appears to be very little space in the design to refit a magazine into the ship.