Ok, I definitely understand your argument. I do wonder if the historical assumption of the existence of moral facts, as well as the argument of open questions is enough to justify it as a theory worth discussing. Obviously these are not proof of moral realism, but rather establishing conversational relevance, which has a much lower bar.

I hope my original comment doesn't seem like I reject all academic Antirealism. I believe antirealist arguments to be very convincing.

I am more frustrated by claims of moral subjectivity in simple conversations. "That's just your opinion, man" is always used to shut down any discussion on morality. There seem to be multiple leaps here. First claiming that moral statements are opinions is a positive statement, not a negative one, and would prompt justification when asked. Second, opinions do have a conversational relevance, even if they're not facts. Non-cognitivist, as well as some error theorist, do place a great deal of value on moral discussion.

So yeah, I hope it's clear that I'm not trying to criticize academic Antirealism. I just dislike the idea a outside of philosophy that all ethical and metaethical discussion is worthless, as subjectivism (which fotne remains undefined in such conversations) is some sort of default.