"All back" is how you say "hit the brakes!" on a ship.
The ship in question displaces 9900 tons (full). It does not turn on a dime. Ordering all back shifted the pitch on the controllable-reversible screws so that they were pulling the ship in reverse (without having to reverse the rotation of the shafts, so it happens pretty quickly).
Maneuvering to either side while doing this would have simply placed a larger portion of the ship in jeopardy by exposing it in profile to the head-on threat.
Clearly you have never sailed a warship. (I have - actually, one that I sailed was a Belknap class CG, a predecessor of the Ticonderoga class, which is what the San Jacinto is).
Because you know exactly how to do his job, right?
He also has a keen grasp of basic physics, apparently. Hint: a warship does not steer like an Indy race car. (I was qualified master helmsman in the USN a couple decades ago. I do in fact know how this works.)