I agree it may be difficult for a utilitarian to fully deceive themselves into giving up their utilitarianism. But here’s an option that might be more feasible: be uncertain about your utilitarianism (you probably already are, or if you aren’t you should be), and act according to a theory that both 1. Utilitarianism recommends you act according to, and 2. You find independently at least somewhat plausible. This could be a traditional moral theory, or it might even be the result of the moral uncertainty calculation itself.
I agree it may be difficult for a utilitarian to fully deceive themselves into giving up their utilitarianism. But here’s an option that might be more feasible: be uncertain about your utilitarianism (you probably already are, or if you aren’t you should be), and act according to a theory that both 1. Utilitarianism recommends you act according to, and 2. You find independently at least somewhat plausible. This could be a traditional moral theory, or it might even be the result of the moral uncertainty calculation itself.