There is probably some correlation between one's profession and fetishes. We already know some programming languages attract certain types of personalities/attitudes so why would that be different elsewhere?
Wow, well, that's one of the more f'd up things I've ever read about. Not sure what else there is to say.
I don't know why the framing. This is easy: review the cases. If it has his hand it's tainted one way or the other. That's it.
See also, I suppose, our discussion yesterday in Firefighter arson a long-standing issue https://news.ycombinator.com/item?id=49130853
Why do I care if someone wants to amputate their own legs? The only issue here is the insurance fraud, if that happened.
The 4chan toaster meme remains undefeated.
https://knowyourmeme.com/photos/1695828-that-is-my-fetish