Probably (and most definitely) the reason the park is closed at dark is because traipsing around the perimeter of the Quarry under the cover of darkness is perilous at best. One miss step and you would be lucky to survive. There must be plenty other places and opportunities that are safer.
I know it is posted that is closed however I have the walk there at night myself if you can find a decent place to park without getting a ticket why not it would be spectacular from that location
Thanks! Your answer is awaiting moderation.