This is a major revision to Lewis' canon, but it's a logical change that other authors have also gone after.
The problem is that you need a longer story to justify the changeover. If this were the right length it would be +1 Moving. As it is, that is canceled out by -1 OOC (Aslan is _never_ surprised and does not make mistakes). So no rating points either way.
If you want to see this handled better, try "And You Shall Receive" by Anne Walsh, http://annewalsh.trycanta.com/fics/And_Ye_Shall_Receive/1