A fair point, but the showriters said that they had known about a very important plot point that occurred in Episode 3, for the past 3 years now.
In the 3 years that have passed since then, it's not impossible to imagine that he managed to finish the books. And that the show writers had already decided on the course their story would take, regardless of what GRRM wrote during that time.
Though I don't think we'll ever know the truth about this, unless Goerge states it officially, or the two books are released swiftly after the show ends.
Keep in mind, one of these writers are responsible for X-Men Origins: Wolverine. And they're now moving on to work on Star Wars...
@bold, considering that character doesnt even exist in the books than it's fair to say they are making their own story.
When the herd loses its way, the shepard must kill the bull that leads them astray.