He was an officer in the US Army, and many officers of equivalent rank in the British Army were nobles, I don't see much difference between Custer and them other than they have their nobility bestowed on them by a monarch, or had inherited it from their parents. I'd have to say, Custer acted more Nobly than many actual Nobles, You see Custer stood on his own heroic deeds and bravery and did not live off of the legacy of his parents, not that he didn't have his flaws, but cowardice wasn't one of them.