OR the angle of climb would increase until the power available balanced gravity(+ lift) at which point the thing drops out of the sky ,tail down, presumably with reduced thrust available due to the abnormal airflow around and through the engines. (effectively a high-speed stall?)
This wouldn't happen while stall protection is still available (which as far as I'm aware it was). I think it's far too simple to assume that the PF had, for some reason, temporarily forgotten the physics of flight. Far more likely to be a combination of factors including (though not limited to); severe spatial disorientation, confusing messages from the a/c and possibly the belief that pulling back on the stick was the best way to recover that particular a/c from the situation he believed it to be in.