Except for the unanticipated effects of white out, would this normally have been a sound assumption?
With the ambient weather conditions, that he had been advised of just prior to descent, to not anticipate whiteout conditions under a 2,000ft overcast, and being advised of light snow showers in the area, would be very rash indeed.
Without any of the AntArctic problems, going below a 2,000ft overcast at 260kts+ in an area you have never before been would to most aviators be a very rash move. Perhaps no problem in a light aircraft on your own, but in a heavy jet with 257 souls aboard, a very rash move. At sometime they would have had to turn to come out of McMurdo base area, the ground would be coming up, and at 1,500ft 260 kts, 200 ton aircraft would not be a position many would like to line up for themselves.