That's because you're conflating two issues. Try this. Is it moral for the government to tell you who to associate with?
No, this has nothing to do with any government but with consistency. I think it's not very consistent for people to rail against moral relativism and at the same time defend the practice to allow every religious faith into the organization (no matter how wacked out they appear to be).
And defending their right to do so is quite a different thing than defending the practice.