Everyone wants to be a victim or find victims.
I think the no harm angle if the only angle that will ever work. If having oral sex has no more effect on someone's life than going to the beach and playing in the sand then what does it matter.
I once heard a girl talk about how she was coerced into kissing someone. I wonder how did kissing someone ruin your life. It's not anything that hurt you. Just like I had to kiss my grandma whenever I went over to their house, but just because I didn't like it doesn't mean it caused any kind of harm at all.