From a previous.
Also relevant, the weather at McMurdo was well below that required for an instrument let down. That was not the case in the previous flights you mention. The only other flight that struck such weather conditions carried out the pre planned sightseeing to the Dry Valley area, and returned to NZ, the pax had been briefed that if weather conditions were not suitable this is what would happen, and in hindsight, and in my opinion, foresight, it should have happened on the flight in question.
The previous flight that diverted went to the South Magnetic Pole area.