Why Japanese battleships stay north in an early-war scenario

Why are Japanese battleships absent from the early stages of the C4 survival alternate-history scenario?

Early-war doctrine kept them from being committed south so quickly, and projecting much beyond March 1942 would outrun defensible historical constraints.

In this scenario, strict early-war doctrine makes a major Japanese battleship deployment south doubtful. Changes in how the battleships were used are placed around 1943, too late for the scenario's early-1942 campaign. Torpedo boats and submarines also need time to redeploy, with their larger role not expected before about April 1942. Their existing commitments and the time needed to carry or sail them between bases constrain their arrival. The counterfactual stops around March 1942 because further predictions would rest on too many accumulated departures from historical events.