I think you misunderstood me. Of course I don't mean that the terms "facts" and "values" represent the same thing. Saying that a preference itself is wrong is nonsense in the same way that claiming that a piece of cheese is wrong is nonsensical. It's a category error. When I say I reject a strict fact-value dichotomy I mean that I reject the notion that statements regarding values should somehow be treated differently from statements regarding facts, in the same way that I reject the notion of faith inhabiting a separate magistrate from science (i.e. special pleading). So my position is that when someone makes a moral claim such as "don't murder", they better be able to reduce that to factual statements about reality or else they are talking nonsense.

For example, "sex is sinful!" usually reduces to "I think my god doesn't like sex", which is nonsense because there is no such thing. On the other hand, if someone says "Stealing is bad!", that can be reduced to the claim that allowing theft is harmful to society (in a number of observable ways), which I would agree with. As such I am perfectly comfortable labelling some moral claims as valid and some as nonsense.