Being unclean is not a penalty, it is a condition. Imagine someone having a communicable infectious disease, or someone that stunk like filth. For whatever reasons, when a person became unclean under the Mosaic law, there were requirements that had to be met to restore his cleanness.
Anyone can see that a law, in order to be enforced, needs some sort of deterrent value to be effective. Without such deterrent value - punishment for violating the law - the purpsose of the law, which is to prevent crimes or actions that offend the society or offend God, is devoided of meaning. You are still to produce evidence that "unclean" is any different than "cerimonially unclean" when it comes to the practical consequences of violating the precepts of the Law.
Plus, you need to justify the desproportionate penalty for eating blood (death) and the penalty for eating unbled meat from an animal found dead in the fields (uncleaness).
Eden