It is a matter of history that the loss of the USS Petrel in the Yazoo to rebel shore batteries not only brought about a crewmen receiving the Medal of Honor (Nibbe) as you have stated----it is also a fact that there was a Medal of Honor recipient already abaord at the time of the Petrel's loss. His name was Bartlett Laffey.
He had been abaaord the MARMORA, also at Yazoo City a short time before and while serving a 12 pounder howitzer asore in support of the landing force he displayed gallantry for which he was awarded the Medal. That action was on 5 March 1864 and his Medal of Honor came through on a General Order on 16 April 1864, not six weeks later.
He may have received word of the decoration about the timehis new ship, PETREL, was lost to the rebels.

The account you posts makes mention of his new rank, the promotion due to his heroism and the Medal. He had risen to Boatswain's Mate from Seaman abaord the Marmora for what he did almost at the same place he he had performed so heroically.

One other crewman abaord the PETREL would one day also have his name associated with the Medal of Honor but that is a story for another day.

Ron Tarburton Historian First State Medal of Honor Roundtable