This is not intended to be part of any competition, just an exploration of ideas!
I think that Sam Harris is generally right in some respects about morality, particularly in that science really can and should inform moral choices. For example, there are matters of cultural and religious tradition that science can show are objectively harmful and cause suffering, such as Female Genital Mutilation, and scientific findings should lead to clear and unambiguous rejection of such cultural traditions.
But, trying to pin down morality is like trying to wrestle a snake. The problem with discussing morality is similar to the problem with discussing free will - there is such a huge disagreement about the meaning of terms that communication can be difficult. I am a 'compatibilist' when it comes to free will - I believe that free will exists in a deterministic reality (indeed, I go further, and believe that free will needs a deterministic reality), but I recognise that this definition of free will is rejected by many (including Harris). The same goes for morality - there are ongoing philosophical debates about moral realism: are moral values things that actually exist in some way, or are they abstractions? While there is continued disagreement about what morality actually really is, science certainly can't determine any moral values, assuming science ever can do this.
There is also the question of what 'well-being' actually is when it comes to morality. We have mostly moved past the view of 'spare the rod and spoil the child' when it comes to punishment of children at school, but there is still a question of whether experience of suffering is 'good for character', leading to a happier later life. The business of how suffering should be partitioned throughout an individual's life and throughout society seems insoluble. To use a simplistic Star Trek scenario - should the "needs of the many outweigh the needs of the one"? Once a decision has been made about weights of needs, then science can inform us, but how to make the decision? Is there a limit to the suffering of an individual we should allow to reduce the suffering of others? Who decides?
Morality is a maze in which we don't even know if there are exits. If someone decides that we should deal with the maze by blasting down the walls, science can help. But is that a moral way to deal with the puzzle?