Social exclusion groups are actually quite normal. There are countries and families after all. Should some be allowed to form social exclusion groups and some not based on race or gender factors? No, Justice is balance. The validity of a group should not be judged on who is allowed into the group but on how they threat those outside the group and contribute to society. Social exclusion groups can actually be a healthy for society and provide a sense of security, and belonging for all regardless of majority or minority standing. As long as a group also treats those outside the group well, then there should be no issue. Pursuing a double standard here is an injustice regardless of intention. Such groups are normally more beneficial for minorities by definition, but can also be useful for those in the majority, who may feel uncomfortable about how to not to offend others.