"Luck" is not a random event. "Luck" is a combination of preparation seeking opportunity, both good and bad.

"Good Luck" in this case might have have been bringing along extra/extended shelter gear since a front was known to be moving into the area later that day and any problems delaying their return from the mountain could easily result in a stay of a day or two (until SAR was able to deploy after the weather passed).

"Bad Luck" might be not bringing along a couple of day's worth of fuel "because we'll be back before the front gets here", i.e., failure to prepare for a scenario meets an opportunity...

Either way, random chance is not the key component of "Luck".

I'm not trying to point a finger at them but rather identify how they would up in trouble, since "but for the grace of God, there go I". At this point the clearest lesson for me to take from this is that "we'll be home by dinner" - which I'm guilty of too - isn't a viable plan.

PS. Even if they had a PLB the batteries might be dead by now if they activated it the first afternoon.

PPS. I*'m not sure a PLB would have saved them. If SAR can't go due to weather, then SAR can't go and you need to shelter for some time. There's a delay between turning on a PLB and the rescue, and if you're on a mountain in weather, that delay might be measured in days.