What does that mean I wonder? Can't do it? Who can't? - Frodo? - or Peter?
This article might word it more clearly, from TORN:
PJ confirmed that the scouring of the Shire is out of the film. He explained that it just didn't fit cinematically and that the scene of the Shire destroyed in the mirror in FotR was their way of paying homage to Tolkien's message about the destruction of the English countryside with industrialization.