Apparently that is the condition of it without any effort to clean it up.
It’s not likely that there have been any other divers down there at that depth in those temps. The author noted the extreme risk and the fact that they had only 25 minutes to get their pics and leave. No time for fooling around.
You can see some specks of algae on the bell though even though almost nothing grows in that anaerobic environment. Even the wood has zero rot in it.