I don't really get the logic of this.
Simple, a cluster can move up comb without breaking, they can not go through comb, they must break and go around.
In a stack of Langstroth boxes, if the bees start winter at the bottom, they are far from the heat that rises to the top of the stack.
That is like having baseboard heat and saying your ceiling is warm but the middle of the room is as cold as the room next door that has no heat.
But in horizontal hives, the cluster is always near the top where the heat is. If the bees don't move horizontally, maybe it's because they don't need to because they are already warm.
Bees don't move for heat, they move for food.
But Michael Bush says that in his Nebraska climate the bees in Langs cluster at the top of the stack and stay there all winter.
Why do you think that is?
Bees are very adaptable and do the best they can with what they have. Just because they adapt and survive to the conditions we provide/force them, does not mean it is ideal.
I look to ferals as my mentor, not a book or expert beekeeper. BTW, this is not meant as a slam to Michael, he is a great guy, great beekeeper and I have a lot of respect for him. That does not mean we agree on everything. As I tell the beginner beekeeping classes I teach. I'm not hear to tell you "the right way" to do things. I'm here to share my experiences and opinions. My goal is to encourage you to think for yourself and do things because you believe in them, not because you were told "that is how to do it" or "that's how it has always been done". Let's face it, there is not just one way to be successful in beekeeping.
Now back to ferals. I have done many removals where the bees had the choice of a vertical wall cavity or a horizontal ceiling/floor cavity. Care to take a guess which they chose?
Now do bees build in a horizontal ceiling/floor cavity? Yes they do if that is the best option they have. Do they survive, sure they do. I have seen colonies that fill up a wall cavity and then expand into the adjacent floor/ceiling space, but have never seen the opposite.