I think the kick off would have been moved regardless of the tv on police advice. Millwall play Burnley at turf moor on the Saturday and would most likely have used the same train network.
As soon as I saw the draw I knew it would be moved from the Saturday especially with the numbers Wigan would have brought to the game. Still think there will be a very healthy Latics following , most will travel by train given its only 10 -15 minutes journey and a half hour walk to ground.