This thread is thoroughly amusing.
People on all sides of the argument essentially state "Racism/culturalism/tribalism is bad, but my sort of racism/culturalism/tribalism is good, because it is for a higher purpose." The purpose being multiculturalism, "equality", "social progress", etc., just as well as national sovereignty, self-determination, or cultural self-preservation.
If you believe in freedom of association (and dissociation), there is no way you can honestly argue in favor of using the power of government one way or the other. If there is a breach in symmetry, it is in that the monoculturalist wants to keep others out, while the multiculturalist wants to keep others in.
Personally, I'd rather be kept out of where I am not wanted than be forced to remain inside a place I do not want to be in. It seems the lesser of the two evils. And, there is a significantly smaller risk for me to be parasitized upon.