I agree with what you are saying. I think Objectivists though work under the idea that Rand has redefined the concept of morality. She assumes there is nothing higher than the human being, so in a sense there is no true universal concept of right and wrong. Her definition of moral then is a system for action that will result in the most productive society. Moral is redefined as "most fitting for fulfilling gour end goal". Which also seems to be the justification for not using force even though it doesn't seem to follow logically from her starting assumptions.