A squared, you can stall at 300 kts, an aerodynamic stall is related to the angle of attack of the relative airflow to the wing chord, not the actual straight line speed. A significant change in attitude at high speed will stall the wing but there would be an initial very high ROC. II don’t think they stalled, LOC due unreliable airspeed seems the likely culprit. The Boeing 737 unreliable airspeed has you setting a power setting and attitude. This will result in a steady shallow climb and gives you time to identify the problem system. If you maintain altitude at about 5000’ (instead of allowing the steady climb) with the required 75 or 80 % N1 ser you will accelerate to 300 kts easy and into the clacker. About 45-50% N1 for S&L at 5000ft. These figures should be known by all 737 drivers......just in case.