What bothers me more and is clear as day in those pictures are things like the screws into the carbon fiber pressure hull holding the screens up. There was someone (ex test engineer?) on reddit yesterday talking about a few things, but what really stuck out was how he mentioned there were a lot of questionable decisions being made that made him nop out of the project. And others mentioning simple things like painting it orange so it can be found on the surface easier were simply not being done.
So, while its possible the surface ship didn't have a sensitive hydrophone recording the dive, which seems almost impossible so i'm going to assume it does, everyone seems focused on how they should be able to hear it implode. Meaning it is drifting about somewhere...
But, I wonder, it seems quite possible to me that the thing simply sprung a leak, and flooded out in a matter of seconds rather than imploding. Once that happened none of the fail safes to surface would work because its likely not buoyant enough once full of water. A microscopic pinhole would probably ablate really fast, but would be completely unstoppable.
Given the hull is only 5" thick, even a 1/2" screw on the inside would be a significant percentage of the way through already.