That definitely all makes sense, except that I think the ambient temperature would be a factor. The air cools as it passes through the venturi and the ambient temp would dictate whether it cools below the freezing point or not. From that point on I'd say you're right that you would need moisture in the air to cause a problem.
I was fairly familiar with all the theory about it, that's why I thought I'd check if anyone has ever frozen up in any conditions? It seems like alot of people have cleaned up everything under the intake manifold and no one's mentioned that they've encountered any problems, at least I haven't read about anyone freezing up.
I think I'll leave it on for now and try taking it off in the dead of winter just to experiment, I'll find out what it'll actually do, if anything.