I am convinced that hatching eggs can endure more cold than many think that they can, and still be viable. A few weeks back, we had a cold spell that lasted about a week. During that week, I would go out to the coop at mid morning to open the pop door and let the bravest ones out into the run. I was finding a couple of silkie eggs on the floor of the coop every morning from the silkies that refuse to use a nestbox. The overnight temps were in the lower teens. These eggs were so cold when I got to them that I was sure that they were frozen. One or 2 of them had even split from freezing. Over the course of a few days I saved up a dozen of these chilled eggs and set them aside and come up to room temp. I had discarded the split/cracked ones. As an experiment, I put them in the incubator. To my amazement, 21 days later, I got ALL 12 to hatch with no problem.
Now I'm not suggesting that everyone chill their eggs before they set them, but I saw with my own eyes, these eggs hatch after having been so cold. The odds of shipped hatching eggs being chilled to the point of freezing and not hatching are near zero, in my opinion.