I think it is more a challenge to the belief that the system is run by people who don't have "the people" and their interests in mind. A quick look at "the people" is enough to cast doubt on that idea. More than 70 million Americans are happy with the current makeup of the Supreme Court, which is the result of the work their representatives did. When the same representatives cut funding for social services, they are again doing what their base wants.What he doesn't really engage with is the idea -- Monbiot's basic view -- that the 'The People' have unwittingly ceded the operation of democracy to a class of political operators who have a vested personal, political, and/or economic interest in the outcomes of the systems they control, one which stands apart from the general interests of 'The People': that the representative models we're currently operating seem to be failing to encourage and reward administrative competence and political honesty, and instead have led us to a point where incompetence, cronyism and corruption are not just tolerated, but appear to be accepted as a kind of norm.
"The People" includes the potential for outcomes we don't like. Monbiot has claimed exactly the opposite. Unless I've misunderstood him, he's saying the unfavorable outcomes are the result of ignoring the will of "the people". He thinks more favorable outcomes --outcomes we agree with-- are more likely by including more people in the decision making.
But, in fact, many times it's exactly the opposite. The US people have been brought kicking and screaming against their will to the acceptance of equal rights under the law, and if the will of the people were to be honored, then in many places it still wouldn't be the law today.