The scenario you point out would only hold good if the ship was initially on an even keel or trimmed slightly by the head. Unfortunately, by the time anything could be done about loosing weight from the bow, the ship was well down by the head. Then, most of the steam had been vented and all available pumps were being used to try and control the flooding. If they had managed to raise the bow at all, it would still have left a considerable net trim by the head and the flooding was still gaining in the large volume compartments aft of WT Bulkhead 'B'.
In fact, according to Wilding, the H&W naval Architect, addition of weight (same as subtracting it) had very little effect. He was describing his calculations showing the effect on trim when the water flooded forward over the top of WT bulkhead 'A' into the void spaces above and forward of the chain locker. I think the effect on trim was about +/- 2 inches.