Maybe they were thinking "these suckers won't know it's not in the film until it's too late and then we can use it to sell more copies of the unrated DVD".
Could be. But i doubt it. I think it's more along the lines of having a huge fight so close to the final third act or the last fight.
Maybe Mangold will explain this in the DVD commentary. Curious as to what his reasoing were for cutting that fight scene.