My understanding of the warre is that it is trying to replicate a natural cavity. If so then I have personally observed hundreds of natural cavities over the years that were way larger than than the actual comb, both vertical and horizontal and the bees did fine. So I would say remove it only if it bothers you as a beek. The bigger question in my mind is whether they have enough stores in a single 12"x12"x8" box to make it through. In my area that amount of space would be enough for a medium sized cluster if it was completely backfilled but any variables such as large cluster incomplete fill or longer than average cold and you would have a dead out. JMO