If there are no human rights a priori of government force, how can tyranny be avoided? In the absence of any deontological justification for normative ethics, there is only virtue ethics.
Natural rights don’t exist, except in the human mind. They are a way for a social species to maintain social cohesion. But, as useful as natural rights may be in deciding how to organize society, they are not fundamental; instead, they are derivative of what humans, in general, desire.