User blog comment:Morganaforever/Is Kilgharrah a good prophet?/@comment-5674726-20121208001120/@comment-5674726-20130526092157

Indecisiveness on the writers' parts seems more likely.

Kilgharrah sometimes treated the future as set in stone but he also acted like there was a way to change things, ie. when he urged Merlin not to save Mordred.