When he grabs the tablet from the statue, you can see the statue is sitting in a pool of water. So while the air might have been -22 F, the ice itself was only 32 F. (Farmers use the same trick to protect their crops from a sudden freeze. They'll spray water over the plants. As long as part of the ice is still wet, lowering its temperature requires extracting a lot more energy to force a phase change. As a result the air temperature can drop well below freezing, but the ice can remain a relatively "toasty" 32 F and insulates the plants from the cold air.)