There is of course the possibility that in early morning thin patchy fog you might be able to see the runway well before minimums. However as you descended lower into the murk the slant and sun caused you to lose visual reference.
I flew an early morning approach last month where we went from Cavok to CAT3 conditions in this way, fortunately reflected in the Atis. So we were doing an autoland. Otherwise it would have been a certain go-around.
It does not change the end result But it would perhaps explain how they got to be where they were.
Equally lining up on a road as suggested earlier would explain it...but at your homebase?