If i understand you correctly, your premise is that if we support the King, he'll stay anticommunist and somehow morph into someone supportive of a democratic government.
I just don't see that happening, and moreover, if the UN can be made to disarm the Maoists (the idea of the UN making anybody do anything is a bit of a giggle, I'll grant you) and if they enter the political process, they will be swamped by the other parties.
No I think if we support the king he'll kill commies. That is my concern, not spreading democracy. It's not America's job to fight for everyone else's democracy, but it is our responsibility to stop communism.
If the maoists are destroyed then the king will have no need to continue to suppress the political parties.