Chris, I think you take liberties with the term “passive aggressive”, but I would rather not get side-tracked with that.
My issue is with the term “non-natural facts”. When we perceive something and recognize it as beautiful, we are recognizing our feelings in relation to that thing, and describing it in terms of its effects on us. Whatever that thing is, such as the Grand Canyon, (which also developed by natural processes) we have the conception of it as beautiful, because we have previously conceived of “beauty” and are elicited by our internal reactions to apply the descriptor “beautiful”. Our description of something as beautiful is a subjective and natural “fact” (if we have a conception of beauty and truly have the internal feelings that elicit that description). That one person thusly considers something to be beautiful, and others don’t, means that what is beautiful or not depends on the individual’s responses. There is no over-riding “fact” that anything, in particular, is beautiful to everyone. Yet, on an individual basis, some things are (factually and naturally) beautiful.
Likewise, concepts are natural facts. They naturally exist when we conceive of them. They only exist (as a physical manifestation) as neuronal and chemical responses within our own skin, (unless we speak of them or write them down) but they are nevertheless, real and natural (not non-natural). Likewise our perceptions are natural facts. Likewise our morals and values are natural facts, in that they are a product of our physical universe and they exist.
If Dworkin’s position, as you say, “shows that secular humanism is not logically scientific naturalism” I question whether this conclusion is founded, in part, on the existence of “non-natural” facts, which I believe to be an erroneous concept.