And this could also be a frozen steering u-joint. If he has the auto hubs and they are still in auto mode the slight turn would get the front axle shafts to start a bad wobble. I've had friends with SD have that, it's not the easiest fix but it is fairly cheap if you can do most of the work yourself. So my recommendation here is to put your hubs in true free or unlock to see if that also eliminates the wobble if the rotation @towcat mentioned doesn't eliminate the problem.