IMHO, If it isn't hindering him, and he's doing well otherwise, why not let him have one litter and see what happens with them. It might not be (would guess probably isn't) congenital, and his offspring might/should be just fine, if not, then you'll have produced some nice dinner fare for down the road. In the mean time, you obviously can't use him for showing, but he might provide you with his own replacement, especially if he is otherwise a show quality rabbit. Just my thoughts.
