After reading that over and over, it becomes even more stupid. Some airline pilot should elaborate on this magic anti-stall device that 'speeds the airplane'.
I will take a SWAG... Disclaimer: I have never flown a Q400 or any other prop than a T-34... But, in the airbus (A-300/310) there are 2 systems designed to prevent a stall..
Alpa Trim: Automatically trims nose down at high angle-of-attack and low speed to counter excessive angle of attack. Alpa trim is only available with the autopilot off.
Alpa Floor: Available below 100 radar altitude and requires autothrottles to be activated (not necessarily in use but armed). Basically when too high an angle of attack is sensed, it automatically commands the max thrust available for that phase on the thrust rating panel. (TOGA/Cruise/MAX)
So there may be a similar system on the Q400 and somebody may have thrown out 20 knots as a random or approx number for airspeed gaining???