This was a terrible tragedy at the time as thousands died. They, all the men recently released as POWs, were desperate to get home to northern states.
Many of them were also greatly weakened and emaciated, after their stint as POWs. When the ship exploded and they were forced into the water, few had the strength to survive more than a few minutes. As the article notes, the Mississippi was experiencing one of its worst floods ever, and the water was still very cold, the result of snow melt and runoff from the upper reaches of the Ohio, Missouri and other rivers that flow into the Mississippi.
And in typical government fashion, no one was ever held accountable.