My understanding is that the 757 would of been carrying out a approach onto a vast unprepared area of ice to the West ?(beyond the no longer used Willys field) of Ross Island. This area is set aside for such occasions when approaches to either Pegasus or the Sea ice runway are not possible rather than attempt an approach and possible crash resulting in blocking of the ice runway. It is basically a blind approach right down to ground/ice or an intentional CFIT. I believe a Safair C130 had to do this a couple of summers back but would not think the outcome would be quite as successful in the B757. The ice is pretty rough with snow drifts and snow ridges (sastrugi) all over the area.
They were fortunate to able to break out of the cloud above the ice and fly VFR to the ice runway. Good end result as it could of ended a lot worse.