Why would they bother? I understand in the case of commercial aircraft because there could be thousands of those aircraft still flying and it would be good to track down what failed. In this case, it’s a one-off, taped together by a goober in his garage. What could be learned that would justify the huge expense of recovering the shards?
To improve the oversight and safety requirements so this doesn’t happen again.
This isn’t the only company using submersibles to dive on the Titanic and other locations.