The detailed findings of the investigation may not be publicly available. Apparently the Navy concluded that everything that could’ve been done to prevent this accident was not being done. If, for example, the sub was not in stealth mode, they could have periodically turned on their active sonar to check the way ahead. I am not a submariner and I do not know what the rules are for operating in the waters where they were. Perhaps they were not following prescribed protocol.
The Navy has always come down very hard on captains for running ships aground or colliding with another ship no matter what the reason or excuse. Not always “fair.” But that is the way it has always been, at least from what I have read. I have no service experience.
P.S. - Chester Nimitz was court martialed for running a ship aground in 1907. He was convicted of hazarding a ship. Despite that, his Navy career survived. Unlikely that would happen today.