I, too, have done Whitney twice - once up by the MR and down the trail. The second ascent was up the East Face and down the MR, fortunately still in daylight. The best way off the hill from the summit is to follow the north trending ridge down to the gully that is the MR. I remember it as steep with loose talus being the biggest obstacle (and of course by that time one is a wee bit tired, as well). Sounds like the person who died might have veered away from the MR and tried directly for the summit. That is much steeper terrain and a rope and companion are a good idea.