I think the point of this post is that people are already doing what they want and, lo and behold, people are behaving morally (for the most part) with or without the permission of moral philosophers. To me, and I'm pretty sure all of you, would still act morally. I would still abstain from murdering people and I'd still tip delivery drivers. We already know (at least the gist) of what morality is.

I think the other point of this post is that even if the relativists were right, we'd still act the same.

(Although, I would be remiss if I didn't mention that I have heard religious people outright say that they would kill and steal if they learned god didn't exist. This is the only silver lining that I am willing to concede to those who say that religion has indespensible social utility; that it keeps leashes on these psychopaths.)