The reason the hypodermis acts as a shock absorber is that

The major part of hypodermis contain fat or adipose tissue that acts as shock absorber.

Explanation:

Hypodermis is a fatty layer of skin that is nearer to the muscle and contain fat and collagen cells.This layer acts as both shock absorber and protects the inner organ.

It also helps to store fats which provides energy to the body.

Hypodermis is known as the store house of lipids and contain adipose tissue containing fat storing cells.

This stored fat acts as energy reservoir,prevents loss of heat and also acts as cushion that protect the underlying layer thus it acts a shock absorber.

this protocol provides a detailed procedure for co-immunoprecipitation (co-ip) to identify protein–protein interactions.