I think of such statements as signaling a preference or emotion rather than expressing a proper belief. Alternatively, the belief that it is wrong to kill people could simply mean that you expect to be in a poor emotional state if killing people occurs.
I think having a new category is unnecessary and a confusion, especially focusing on ‘moral beliefs’ that are simply a subset of preferences, or ‘beliefs about my emotional response to a course of events or situation’.
I still think Ayer’s chapter on ethics sums up morality pretty well, at least as most peole use the term. Is Harris referencing something other than an objective set of values? It seems he may be committing one great naturalistic fallacy if not, and if he is I wish he would ditch the term.