Again, read my post.
Way before things went pear-shaped, the CA had printed proof that nothing is allowed to land in CHS after midnight.
The radio exchange en route with JAX proves it- they confirmed they had no idea the airport was closing (in two minutes, when queried.)
The information could have easily flowed from the CA to DX, in the form of, "Hey, this here release I signed? The one what says I am aware of all factors applicable to this flight? Yeah, it says CHS is closing. Call and ask if they will keep it open, if not- we're back to the gate."