I went to the site.
"Most backpacks have a pocket on the side to hold a bottle and those pockets were designed to accommodate a Nalgene bottle because hikers have trusted Nalgene for over twenty years."
Does something need clarification with the system? Carrying your hydration bottle in your pack next to your back is what one should do in cold weather to limit freezing. Apologies, but I am confused on your point. I don't currently have any affiliation with Whittaker Mountaineering, it's just one of the few places in the states where you can get that particular setup that I know of. If they give bad info, that is their problem, but the system has worked for me in some pretty harsh environments.