Today I bought a chicken that was slaughtered less than an hour before, so it was still warm. The shopkeeper said it needs to stay in the freezer for a couple of hours to cool off before I proceeded with cooking. Why is that?
The consensus from sites I have seen that appear fairly credible is that you need a resting period to avoid toughness in the final product. I speculate this is to allow rigor mortis to come and go.
According to Girl's Guide to Butter's article Chicken Butchering 101:
Similarly, The Self Sufficient Home Acre's How to Butcher a Chicken article says: