Answer:  You are specifically asking about FAR 42.302(c) being used to delegate contract administration duties to the ACO. The duties you mentioned could be delegated, but FAR 42.302(c) is not what allows them to be delegated.  FAR 42.302(c) is telling you if the PCO has not delegated the responsibilities and they are not responsibilities that are required to be delegated, then anything they do not delegate they, the PCO, would still be responsible for doing.