Suffice it to say that I don't agree.

That's a position, not an argument.

Having a consistent definition of exists would help immeasurably in clarifying positions on the moral realism / anti-realism debate.

Boooring... I care about accurate models, not choosing between two equally untestable positions.

You do realize that the standard understandings in the moral realism debate would say that referencing wrongness to a particular (non-universal) source of judgment is an anti-realist position?

Why should I care what a particular school of untestables says?

Saying that right and wrong are meaningful only given a particular social context is practically the textbook definition of moral relativism, which is an anti-realist position.

Again, I don't care about the labels, I care about accurate beliefs.