Massaging scar tissue after an injury or surgery is essential to restoring and maintaining elasticity and function of the soft tissues involved, including skin, muscle, connective tissue, organs and lymphatic vessels. It is especially important after a Caesarian section because the location and depth of the incision impacts on so many different structures in the low back and pelvis. See this excellent article below for a more in depth discussion of how and why to massage scarring:
http://intuitivehandspt.com/the-importance-of-massaging-your-c-section-scar/