Why is the walrus not scientifically classified as an omnivore?

Answer

Digestive system not structured for large plant cellulose processing.

An omnivore implies regular, significant consumption of both animal and plant material; however, the walrus's digestive system and dentition are not structured to efficiently process large quantities of plant cellulose.

Why is the walrus not scientifically classified as an omnivore?
dietanimalmammalwalrus