Is it fair for the person in southern California to get an extra couple days to revise because others are going through a hardship? Probably not. I would want them held to the original standard (similar to what the grandparent is saying).
That's the tension I see with this decision. And how do we handle the special cases with teams that are split between coasts?
I don't think one rule will be completely fair, and I would ask pg to apply wisdom regardless if the official date changes. The date is just a date. It's better described as a spam filter than a deadline since YC accepts late applications anyway.