I don't think outsiders should interfere much in this situation, as it can easily backfire and feed a nationalist reaction. I do however think that internally, people should agitate to end the monarchy. Even if as some commentators point out, the monarchy is presently a stumbling block for western liberals, it can easily change allegiances and is not a reliable partner. Thailand is for example, currently looking to join OPEC (alongside BRICS it seems, trying to play both sides).

Like other monarchies (Saudi Arabia), they are basically being opportunistic, and it just so happens that the winds of history are currently blowing in favor of China. I believe that in a serious confrontation between the West and China, monarchies will be very unreliable partners and could even be subverted by the western powers. That's not saying that a republic will behave better, or even have a rational leadership (ex - India), but the revolutionary momentum generated by abolishing the monarchy will probably win the workers some concessions and likely improve the governance of the country for a while.