There seems to be some confusion - when I say "an objective morality capable of being scientifically investigated (a la Sam Harris or others)" - I do NOT mean something like a "one true, universal, metaphysical morality for all mind-designs" like the Socratic/Platonic Form of Good or any such nonsense. I just mean something in reality that's mind-independent - in the sense that it is hard-wired, e.g. by evolution, and thus independent/prior to any later knowledge or cognitive content - and thus can be investigated scientifically

I think you are bringing up two separate questions:

• Can science tell us what we value? This question do not rely on whether morality is universal, any more than the scientific investigation of hippos food preference rely on elephants having the same.

• Can science tell us what to value? If I have not misunderstood Harris, his central claim in The Moral Landscape is that science can. Harris have been criticized for not actually showing that but rather if one presupposes that maximum "well-being" (defined) is morally good - suffering bad - then science can tell us what is moral good/bad action. But this is no different form claiming that if we define morally good the amount of paperclips there are, then science than tell us what is good/bad action.