edit:
I'm tempted to just be excessively dismissive here, but I realize that Exodus and similar groups are able to brainwash folks into genuinely believing what they say, as horrible as it is.
That said, I don't think it's an argument that supports your cause any more than if you were arguing that the existence of feral children means you can "successfully change" a child to be an animal. The fact that you can abuse someone's sexual proclivities out of them is at best irrelevant. To put it another way: If I'm able to convince someone he's a teapot, that's not evidence supporting the idea that non-teapotism is a disease that needs curing.