I’ll try.
The elevator neutral shift is made up of two components, the first is due to stabilizer position and the second is controlled by the flight control computer.
Your extract was only referring to the stab input to neutral shift and does indeed only move the elevator upwards. The FCC input moves the elevator up or down as required depending upon Cof G and flap position. The total input is the sum of the two and may cause the elevator to move up or down.
S&L