Because constantly being in a state in which he is attracted to children substantially increases the chance that he will cave and end up raping a child, perhaps. It's basically valuing something that strongly incentivizes you to do X while simulataneously strongly disvaluing actually doing X. A dangerously unstable situation.
Sure.
So, let me try to summarize... consider two values: (V1) having sex with children, and (V2) not having sex with children.
There's a recent science fiction story that I can't recall the name of, in which the narrator is traveling somewhere via plane, and the security check includes a brain scan for deviance. The narrator is a pedophile. Everyone who sees the results of the scan is horrified--not that he's a pedophile, but that his particular brain abnormality is easily fixed, so that means he's chosen to remain a pedophile. He's closely monitored, so he'll never be able to act on those desires, but he keeps them anyway, because that's part of who he is.
What would you do in his place?
In the language of good old-fashioned AI, his pedophilia is a goal or a terminal value. "Fixing" him means changing or erasing that value. People here sometimes say that a rational agent should never change its terminal values. (If one goal is unobtainable, the agent will simply not pursue that goal.) Why, then, can we imagine the man being tempted to do so? Would it be a failure of rationality?
If the answer is that one terminal value can rationally set a goal to change another terminal value, then either