I agree with your contention, as I understand it, that those who have been using the term "objective," as a description for a morality that is agreed upon, rather than the commonly understood meaning that it is an imposed metric, are creating a semantic problem. I would add that this is especially true, when they are posting online, in lengthy threads, that may not be read in their entirety by newcomers to the discussion, who may have missed any kind of special definition that was given during the discussion, and assume the common definition.
I can't offer a word, off the top of my head, that would be a satisfactory replacement.
As I stated in my last post, I would take the issue a step further, and suggest that perhaps "morality" is too broad a term, for the diverse nature of the subjects it is applied to, which can often bear little resemblance to each other. But we work with what words will be best understood. So if I say that there is no objective morality, I am not contradicting Dillahunty's contention, but actually talking about a different subject.