In your view, homosexuality only exists when it's defined by acts with men over the age of 18?

It must follow from your view that it's not just priests, but straight men everywhere, who are attracted to teenage boys.   

Frankly, I find your views to be a bizarre take on male sexuality.

I have what I think is a much more rational view:

Every priest who molested a boy is a gay man.

If progressive Catholics really wish to understand the sex abuse scandal, they have to acknowledge that basic fact.    To suggest, as you do, that abusing priests were all straight men, and that straight men often lust after boys, is simply a wrong view and not helpful to preventing this kind of thing from happening again.