Perhaps the best answer to the question about legality, is a quote from Douglas "Tin Legs" Bader. "Rules are for the obedience of fools and the guidance of wise men." In simple terms, if they managed to do it without causing any trouble, they must have been wise enough.
I see Mr. Bader's quote as being able to be interpreted two ways: Wise men will generally do what the rule said anyway, to avoid being in the situation the rule is there to prevent. Fools may get away with silly things - until they don't.
So it was done to get somewhere before it closed…safe?
There have been a number of times in my GA flying career where I have had to land elsewhere and spend the night because "trying to make it" would have been unwise. Pilots must be prepared for this for cross country flights....