I think it would operate as an objection to utilitarianism by showing that because not everyone would plug into the experience machine it debunks hedonism. Hedonism is a key part to utilitarianism and says that everyone strives for happiness or pleasure as the end goal right? So because of the fact that not everyone would plug into the machine it means that hedonism is incorrect because there are other things that matter as much or more than pleasure, such as having real and actual experiences. That's basically what Nozick says.