Someone who seeks to mask their discriminatory words and actions with regard to homosexuality beneath a veil of high minded moral disapproval. Someone who believes heterosexual couples are superior to homosexual couples, and therefore deserve respect and rights that are not afforded to heterosexuals.
Person 1: Can you believe that guy? What a homophobe!
Person 2: No, no! He's a 'heteroseparatist'.
Person 1: Oh, so he's like a homophobe, but with less integrity and honesty?
Person 2: Yep.