One reason to be more concerned about privacy in a nationalized communication network is because it removes a middle man - one who cares at least a little about

One reason to be more concerned about privacy in a nationalized communication network is because it removes a middle man - one who cares at least a little about PR backlash - from the current system. In a nationalized system, there is likely much less friction for a bureaucrat to block entire classes of content than there is today (where they need to deal with a handful of companies whose goal is to make money rather than silence dissident opinion).