These protests seems to be fueled by a mix of anti-Palestinian racism, sexism against a high profile woman, and that there is still enough reverence for the monarchy among the tribes that they don't want to attack the monarch directly. As with so many queens throughout history, she is an easy target on which to project anger without attacking the king.
http://in.reuters.com/article/2011/02/08/idINIndia-54745020110208