You're right that the service bulletin doesn't talk about selecting selecting a sufficient nose up trim because control of the aircraft using manual trim is a continuous action performed in combination with the pitch up command of the control yoke. Just pulling up on the control column and activating momentary manual trim isn't sufficient or intended. I understand why people think the checklist implies that performing a STAB TRIM cutout occurs instantly after the autopilot is disengaged because of the "if runaway continues" language.