In many professions, it simply means that someone wanted him gone, and after looking for faults they finally nailed him on something that everyone does occasionally.
But I don’t know the nature of submarines. Perhaps he was a bad commander.
He was a very bad commander to let his crew slack off like that.
Those guys are beyond intense. You are talking about nuclear power, nuclear weapons in a vessel that is subject to environmental conditions beyond your comprehension. Attack boat skippers are the creme-de-la-creme. Best of the best.
I am amazed this guy got command at all.