I spoke to Matteo Meglioli (Mosti's tech director) about this at the last Winestock. He told me that it is a filling/shipping issue. The bags they can buy are tall, rather than squat, with the fill spout at the top. This works well with the automatic filling equipment they use. If the boxes were to stand vertically, however, they would not palletize well for shipment to retailers like George, and would tend to take a beating when shipped to us. They are working with their box manufacturer to get cutouts to pull the spout through so the box can be stood on end for siphoning.
So how do I do it? I open the box and remove everything except the juice bag. Then I close the box back up and stand it on end with the spout up. Open the box back up and let the bag gently "fall over" so the spout is lieing to the side. Then, holding the spout in one hand, I lay the box back down, keeping the spout up. Finally, holding the spout in my left hand, I pop the cap, insert a pre-sanitized autosiphon and into the primary it goes.
It's kind of hard to visualize, but easy to do. If George wants to donate a Masters Edition kit to the cause I'll demonstrate at the next Winestock. In fact, George, I'll be in the store next Friday morning and if you want to video it I'll demonstrate.