It matters to reality.
Or, if we consign reality and logical proofs to the quaint dustbin of history, it still matters to current pragmatic political theory. As has been said, Harris' "Scientific answering of moral questions" seems wholly Western-based (except for his Buddhism fetish). He'll continue to shoehorn his distaste of other cultures (particularly Islam) into his supposedly scientific, objective moral landscape.
Even more dangerous, he IS actually seeking or becoming a title of new Prophet, with Science in the place of God. The analogy is apt imo because neither religion, nor Harris' ridiculous claims are grounded in logic or science, yet both seek to be a transcendant and wholly truthful idea.
I'm reminded of a baffling objection to some philosophical positions: "Then what does it offer?" As in science, philosophy isn't intended to provide a comfortable blanket. Their purpose isn't to offer anyone any easy position to lie in. If a particular science or philosophy can't "offer" any easy comfort, that doesn't mean it's wrong. And if idiots who exploit them can, that doesn't mean they're right just because/if this makes adherants think they have an answer. Some things don't have an answer, and never will.