>> emotional response (which motivated the behavior) is valid and natural.
This is obviously nonsense. If an old woman falls over and breaks her knee, and one's emotional response is happiness - they have real problems - it's not natural or valid to feel that. If the idea of choking women to death makes one feel excited - no it's not natural or valid to feel that emotion, they have serious problems. One could go on.
Maybe you haven't met any really bad people in life - when you do you will often find they have very strange emotional responses to things.
> they have serious problems
Or they are practicing buddhists. Or victims of trauma. The former doesn't need (but won't mind) validation, the latter does.
I guess I should make explicit my general assumption that we are not talking about psychopaths given the overwhelming odds that a given individual is not a psychopath. That said...
> If the idea of choking women to death makes one feel excited - no it's not natural or valid to feel that emotion, they have serious problems.
I disagree. That is surely a natural and valid emotional response for whatever reason this hypotheticals individual feels it. Yes, they also surely have serious problems but I contend that said problems are obviously what lead to this "very strange" emotional response. Their problems are also valid, regardless of the personal damage (read: devoid of outward violence) they cause.
In this case, the response might affect their behavior such that they actually do it and that would obviously be tragic; that behavior is not valid regardless of the emotions (or lack thereof) which motivate it. Otherwise, speaking of their emotional response, I don't see a reason to condemn them for a reaction they have such little control over.