AFAIK, Libertarians are not Utopians. If there is a choice, they prefer decentralization and secession. Underlying reason is not important (Ethnic and religious, or ideological). Besides, from what I know, in large sovereign states and large democracies minority or ruled ethnic and religious groups always suffer. Because they will be imposed the ruling groups culture, language and curriculum. If they want, they should have at least a degree of self control and identity.