I said should and should not are useless "in the absence of a specific objective". But, as you suggest, they are useful in the context of an objective, e.g. I should not push old ladies into heavy traffic (implicitly: because I prefer not to live in a world where old-lady-traffic-pushing is a commonly accepted pastime and I believe that not indulging in old-lady-traffic-pushing makes such a world more likely to exist in the future, given some assumptions about the dynamics of social systems).
So, I agree that morals express should and should not sentiments. I also agree that individuals can hold morals, in the sense of personal codes of behavior. However, my original point of contention was whether or not natural and human rights exist in the state of nature. A discussion of morals ensued because you implied that an acceptance of the existence of morals was somehow related to an acceptance of the existence of n/h rights.
Morals and n/h rights are fundamentally different in that morals are intra-personal, while rights are necessarily inter-personal. So, while I would accept that morals can exist, in the sense that individuals can desire particular states and derive codes of behavior for making these states more likely to occur, these sorts of morals are not the sort needed to make the functional similarity between morals and n/h rights that you previously suggested meaningful.
These form the key points of our disagreement: that morals act like n/h rights and that n/h rights exist. While you may not have intended to support absolutism, based on the way in which people typically discuss n/h rights, and based on the formal definitions of these terms that I've seen, I'd say that any support of n/h rights is implicitly support of absolutism.