Actually, these conditions don't look very good at all, do they?
There's a significant amount of evidence that they were referring to the conditions ahead that they would soon be in as opposed to the conditions they were in at the time. As i said before, Collins started planning an escape maneouvre the second F/E Brooks said "I don't like this".
My guess is that they weren't attempting to escape high ground as much as get out of the conditions that were affecting their perception.
Framer, the only checks they had at the time were visual, and it's just a tragic coincidence that they happened to be at the one spot in the sky where it was possible to mistake the set of features defining Lewis Bay for those defining McMurdo Sound.