Perhaps I'm missing something here. It's not like he vacated it and moved up. He successfully defended it aginst N'Dou. What happened? It wasn't on the line against Hatton, was it?
I think they stripped him of it when he wanted to face Hatton. Can't remember what their problem was, maybe he had another mandatory or something.
The IBF was trying to force him in a rematch with Ngoudjo since the 1st fight was controversial. He refused for the Hatton fight and ended up getting stripped.
I think they tried to force him to face N'Dou (not N'Goudjo) again. I remember him saying something like "Why should I have to beat the same dude 3 times in a row?"
IBF wouldnt let him fight the Linear champion Hatton , and stripped him , seems the best belt to have if there is one is IBO , has a Champion , but non of these terrible mandatory mismatches.