“ A cell router is responsible for detecting failure within a cell (Zombie outbreak) and rerouting requests (Citizens) to other neighborhoods.”

Misleading. The difference between a pure horizontally-scaled cluster and cell-based architecture is that traffic destined for a compromised cell does not get routed to a healthy cell. Fault isolation (preventing noisy neighbors and poison pills from spilling over to progressively more cells) is a primary tenet of cell-based architecture.