If bones can't exist at Titanic's depth, how can they fossilize in the deeper Diamantina Zone?

It is commonly reported that bone remains will quickly dissolve below the carbonate compensation depth and that's the reason why no bones can be found in the Titanic. However, I've never seen supporting calculations with dissolution rates and frankly I've been a bit skeptical this would happen so fast.

The recent discovery of A 5.3-million-year-old deep-sea whale necropolis in the Diamantina Zone shows whale falls undergoing fossilization at depths way below the average CCD (which may be locally lower? This would surprise me).

Critically, the ultra-low regional sedimentation rate close to the Diamantina Zone (Broken Ridge, 0–5 Ma, 0.05–0.55 cm kyr−1)40 implies a prolonged exposure of the skeletal remains at the sea floor: one that would probably last more than several hundred thousand years at least. On slopes or uplifted sea floor zones, skeletal remains may remain exposed for extended periods: up to 5.3 million years, according to our dating data.

Now this is followed by the acknowledgment that the whale bones they found are ideal for resisting degradation and that the environment supports rapid fossilization:

The fossilized remains we observed are almost exclusively beaked-whale rostra, some of which have the highest bone density and mineral content among extant vertebrates. This high compactness probably inhibits rapid degradation, with long-term preservation on the sea floor being further enhanced by the progressive accumulation of ferromanganese oxides both within the bone matrix and on the outer bone surface.

But still, Titanic has been down there for just over a hundred years. Would human bones really be dissolved by now?