Thanks Heiwa for the points you raise. I think we have different definitions of stable. For me, stable means a stable state where it will stay in that condition for a substantial length of time barring further disaster. Days or weeks or longer. A ship progressively flooding as WT compartments overtop and fill is not stable, it is certainly sinking and losing its remaining stability. In the case of the photos you cite, snapshots in time, at those moments it has stability remaining, and hasn't capsized yet, but its future is guaranteed to be on its side like you cite for HFE. Sinking slowly is not a stable condiiton, it is doom, just much more slowly than HFE. As you state, if it were in deep water, it would have gone 180º.
Why? HFE had a massive amount of open free surface in the car-deck and very rapid flooding from the bow. HFE probably had 50% of its internal volume/GRT in one big open space close to the waterline, perfect for free surface to rock and roll and flood. Combined with pitching in heavy seas, the free surface put the bow right under, scooping in more water, amplifying the effects and spreading it quickly the full length of the ship.
Other then the engine rooms, CC was flooding into many thousands of small compartments, and being a ship of vast volume (buoyancy), CC probably had less than 2-3% of its internal volume/GRT in any single space, including the engine rooms. Its just that CC's thousands of spaces weren't all watertight, only the lowest ones. Flooding occurred slowly and progressively, much more like the Andrea Doria or Titanic than HFE. This is further observed by the gradual shift back from near 90º when it first capsized to its current position of about 60º-70º as the remaining small compartments below the new WL lost buoyancy, ship finished sinking and took on the angle of the bottom.