A weapon is tool used to cause harm, it will always be offensive. Regardless if you use it to save another's life, any action you take against an opponent is always an attack. Look at history even. Every weapon in the history of mankind was abused. If I taught a farmer how to use a scythe meant for shearing wheat as a weapon, I can guarantee you he'd reach for his scythe if he wanted to hurt someone. The same goes for the Force; once you use it as a weapon, you will always see it that way.
I apologize if I wasn't clear on this. I didn't mean it in a game context. Let's take a real life example here. Imagine the aforementioned rapist used somewhere above. Now imagine you had a gun. How could you possibly use the gun to shoot the rapist if you did not feel some negative emotion toward this rapist? Sure, to use the gun you need to know how to pull the trigger, but why would you use it in the first place? You would shoot him because you were angry at what he did, or maybe because you hated him for being an animal. Now, the Force isn't just a gun. No, it's much more than that. The Force is something much more powerful. You may have heard this once, "With great power comes great responsibility". It might sound corny, but it holds true here. Treating the Force like any other tool would be sacrilege to a Jedi. Using it to kill is wrong, no matter the how or why of it.
I'm glad you realize that mastery of such dangerous lightsaber arts is no small feat. There are what, two Jedi who have mastered the Vaapad? So close to the Darkside is that form, that one Jedi was consumed by it. Is it any wonder why? Resisting the Darkside is hard, even for some of the strongest Jedi. And we're not even talking about using the Force to directly harm someone here, this is dealing with focus and emotion! How much harder, then, would it be for a Jedi to master such techniques that use the Force to directly hurt or kill someone? If only a handful of Jedi can barely manage to master a lightsaber form that flirts with the Darkside how can any Jedi possibly begin to suggest using offensive Force techniques? Restricting any offensive use of the force is meant to protect the Jedi who do not have the will to resist the Darkside after tasting it.
Luke didn't have to choke them. He could have used the Force to paralyze them. So many options, so many alternatives, but he resorted to violence. Why? Because it was the easy way. It was not the Jedi thing to do.
First of all, what says using an offensive power against an opponent so much more powerful would even suceed? Although I see how an opponent would be surprised to see such aggressive use of the Force by a Jedi. But why would the Jedi even consider using the Force for offense? Is it because he is afraid he will lose? Or maybe he is angry that he is being beaten? Even against a powerful foe, all a Jedi must do is concentrate and keep all emotion in check. Anger makes people more prone to make mistakes. Who do you think will slip first? The calm and focused Jedi, or the enraged dark Jedi, who is slave to emotion?