I'm guessing that your last quote tag was in fact a question. This was not a normal, routine flight - but the procedures put in place by ANZ meant that for line crews it was accepted that it might as well have been. The "safety" altitude was explicitly rescinded in the briefing - what part of that is difficult to understand?
As PIC, Collins had faith in the people that had briefed him, the company he worked for and his own abilities. Going by character testimony he was a cautious and meticulous pilot, well regarded by everyone he worked with. There is nothing in the record to suggest that he was anything other than that when he boarded the DC-10 that morning. He was not expecting to have to improvise and followed the advice and information he was presented with - and I emphasise this again - to the letter. If he had experience of the Antarctic before then your argument would hold ground, but the fact is he was not - however he was told that if he followed the instructions (and computerised flight plan) given to him at the briefing he would be safe. ANZ changed the flight plan without telling him, did not communicate the change in co-ordinates to the radar controllers at McMurdo and did not impart to him the vital knowledge of whiteout at significant altitude - they set him up to fail.