Current constitution require 2/3rd votes to dissolve a government. It also means a party needs 2/3rd seats (401 seats) to form a govenment. So Maoists need support of another 181 seats apart from their 220 seats to stake claim on government on its own.

Nowhere in the world is the system of the party having highest seats have mandate to do everything. What if Maoist have got 201 seats and NC and UML have 200 seats each in the assembly? It's democracy and not communism.