Why did the Air India pilot push the plane's nose down even when it was dropping 300 ft?

Air India's plane, which dropped 300 feet, experienced a pitch increase after losing control. A second later, the co-pilot pitched it fully nose-down, but was unsuccessful as control surfaces were unresponsive. This is because pitch doesn't single-handedly determine an aircraft's altitude, and a nose-down input can be necessary to counter an aircraft pitching upwards and losing speed and control.