17 is pretty young for screwing, yes. And you're picking extreme examples to support the notion that adults banging children isn't a bad thing.
I went with minors. You're the one that wants to make it about children, I presume for the emotional appeal.
OP just went with "get freaky with" and now here that is banging. To me, your rebuttals to this are all demonstrative of why anti-homosexual types have a legitimate case. It's all about manipulating the narrative, and not realizing how that really only impacts own self. So the projection part is key, as in you saying I'm picking extreme examples. Heck, everything you've said changed how I originally worded my point.
And you still haven't shown how the point I raised would actually impact your life. You've made a claim that it would, but that is just as easy to do with anything including homosexuality. Just claim it is very immoral, inherently dangerous activity, and makes us all unsafe if we allow that in our community. Or how the projection part of the equation has to work to maintain the appeal to emotion inherent in what OP is getting at, but that apparently author of OP hasn't clearly thought through.
To perhaps help with what OP is getting at, it is (a lot) like saying that the way I (hypothetical anti-homosexual) imagine homosexual sex to be, it is inherently dangerous, and undoubtedly perverted, thus very immoral for anyone to allow that. If anyone is allowing this sort of immoral behavior, then all immoral behavior is being allowed. Therefore to make sure our community/society doesn't go to hell, it is in our best interest to not promote this as okay activity and if anyone is caught doing it, they ought to be socially condemned at the least, and prosecuted under obscenity / sexual predator type laws to prevent all people from going in this direction, or as much as we can possibly prevent it.