The old "hate the sin, hate the sinner more" at work.
They don't hate their daughter. That's nonsense. They love her but they don't love the sin of homosexuality. There IS a difference, you know. My son is living with his girlfriend. I love them both but I hate the example he's setting for his children. People suffer spiritually from sin. Christians know that and we would love to see our kids delivered from their sexual sins. Sometimes harsh methods are needed; sometimes not. It's easy to sit at FR and judge what the Keyes' and other parents are doing. Not so easy to have to go through it yourself.
You need to learn what love is.