Paladins choice

[Ormur]

That is one possible interpretation, but it is certainly arguable against.
Or maybe it is evil to NOT torture under such circumstances... by labeling the torture of child rapists wrong and evil and forbidden you are directly causing more children to be raped. Which is an evil act.
This is NOT justifying "torture the evil act", that is saying that NOT torturing is an evil act.

There is nothing to indicate that torturing child molesters reduces molesting. When people are committing a crime most of them aren't really thinking about the consequences, that's why they commit crimes. Deterrence isn't that useful. Perhaps horrible torture would deter a few but at the cost of making horrible torture a part of your justice system, an accepted routine act. The evil caused by that could just as well be greater than not doing anything.
There are also usually ways of combating crimes that are both good and effective. You mentioned prison rape but where I live that's not a big problem and our crime rate is much lower than in most of the US. There may not be a direct link but it shows that you can have low crime without prison rape. Conversely you can probably also have low rates of child molestation without horrible torture.

And what the hell is wrong with JUSTIFYING actions? You better have a pretty damn good justifications for moral choices you make otherwise you are just randomly doing things without sense or reason. Justifying things means "making them just", and its a pretty good term because it can do exactly that when done CORRECTLY.

My point would be that you can justify the use of evil acts as necessary but that doesn't make the act good. Heck you can justify genocide by saying it's for the greater good. This touches on that point in most cases you can't accurately predict the consequences of your actions. You have to think whether the act is good in itself. You have no way of knowing your horrible torture will result in anything positive but you definitely know that you just did something horrible. I think with the absolute morality of D&D this would have to be the benchmark. What if your torture wasn't an effective deterrence, does the Paladin fall when the crime rates for the next year are tallied? Is the intention of torturing for good enough, wouldn't that not allow for a whole slew of horrible "good" acts by the well intentioned extremists of the world?

Torture is evil. It leads down a slippery slope, it's ineffective, it's the barbaric calculated infliction of pain on a human being. Balancing such evil acts against good intentions might slip as neutral. Who know maybe there are times when you need a morally neutral anti-hero to dispense with the pleasantries but that doesn't change that in general such actions cause pain and misery and that we'd all be better of if everyone were good. In a cynical setting (most likely including real life) being good may not be the obvious moral choice and being good is probably pretty hard.