I'm actually not sure if carbonated beverages freeze sooner or later than non carbonated ones. I do know they usually don't freeze as "solidly" (you get loose lacy ice, rather than a solid block), and can be more dangerous since, the drink is already under pressure and the extra pressure can be enough to rupture the bottle. A few weeks ago I had a really scary experience when I woke up one morning and realized I had left a full sealed glass bottle of Borjomi (that salty mineral water I mentioned before) in my window well overnight (during the winter I often stick beverages in there to chill them) and the night temps had cause it to freeze solid. Fortunately there was enough empty space left in the bottle to cover the expansion so I was not showered with glass shrapnel as I slept (I should mention that due to an incident my freshman year of college I tend to keep the window by my bed open when I sleep even in the dead of winter.)
The reason I think that the soda isn't effected is that some of those buyers I mentioned are probably big enough that they have their OWN shipping trucks, and those trucks might be thermally regulated to keep the soda from freezing.
To be honest I am trying to link two piece of information together that may be unrelated, the fact that Maine Root has suspended shipment of ALL of their beverages due to the cold weather (which could simply mean that whoever does their shipping (UPS, FedEx USPS etc.) doesn't use temperature regulated trucks, with the fact that the store is taking unusually long to get a restock. The two could be wholly unrelated.
Actually a part of it is wishful thinking. I WANT that to be the explanation, because the other logical one is a lot worse from my POV, that the AP has decided it doesn't want to carry the stuff anymore, and the maple on the shelf is simply a matter of getting rid of what they already have on hand. That's worse of course because it means they will NEVER get more in, and using the mail order when it does come back into feasibility becomes my only, rather expensive option (because the bottles are glass, the shipping cost of a 6 pack of lemonade is basically as much as the cost of the pack itself so I'd be looking at paying about $4 a bottle.
And actually there may be proof that the latter case it the real one. On the site I notice that the lemonade bottles recent had their labels redone several months ago; the bottles I have seen in the store are still all "old" ones.