The quote is actually a perfect example of how Scalia rules, he confuses his "moral feelings" with the law. A person has the right to moral feelings against homosexuality, just as I have the right to have moral feelings against said person. However, one cannot justify a law without demonstrating a legitimate state interest. There is no rational argument for how the state benefits from persecuting homosexuals.
Scalia's argument is so obnoxious because it provides no useful legal test. Every single action you can think is considered immoral by somebody, you could use his argument to justify literally any kind of law.