If the maoists are destroyed then the king will have no need to continue to suppress the political parties.
Communism is rarely attractive for a majority of any people in a democratic society. In the Nepali case, the devil is in the details: for example, will the ceasefire allow civil government to be restored in rebel controlled areas? I don't pretend to be an expert, I just think the Indian interest and that of the US are substantially similar here.