I may well be mistaken in this, so please correct, but I understand that they were on a one day trip, leaving at 1-2 AM and planning to return mid afternoon (say 2 PM) that same day...At most, then, you would probably carry only emergency bivouac gear, not the load than would accompany a planned overnight.

Our deft attempts to analyze this situation are hampered by a lack of real information and an abundance of speculation and assumptions (including mine!)