The Captain was by definition at fault, no matter what the tanker did. He will almost certainly be disciplined, and he will probably retire rather than face a paper-pushing career in disgrace plus the guilt of his men dying when it was his job to prevent their deaths. Some other officers will also face severe to career-ending repercussions, including possibly the XO (even though he only had two months on the job), the Navigator, the OOD, and perhaps other officers. This sort of thing gets ugly, quickly, whether an officer did something stupid in the moment or merely had a responsibility to ensure training that would have avoided the collision.
These board of inquiries are harsh by nature, and intentionally so.
When an officer takes command of a vessel, he is in charge of United States territory, and there is a lot of responsibility that goes along with that, apart from the possibility of damaging the vessel due to incompetency or accident.
They know that when they take command, and when something happens, there is merciless armchair quarterbacking. That is by design.
If you are the Captain of a US Navy vessel, then you know in advance, you are not going to get any mercy, forbearance, or consideration from one of these boards. You just don’t expect it.
It does occasionally happen, though. Chester Nimitz as a young Ensign, ran the USS Panay (not the same one the Japanese destroyed on the Yangtze River) aground in the Philippines and appeared before a board of inquiry. He argued his case so convincingly (that the charts were outdated) that they actually let him off. Very rare.
It did have an effect later in his career on his conduct as a Captain and Admiral, where he was known to show leniency for first time offenders. One of his favorite sayings was “Every dog deserves a second bite...”