I would agree with the most of what you've said, however, I feel the need to point out that torture porn is made with exactly this in mind, and dare I say, only that in mind, so routes like using only first four objects wouldn't even exist in here, if that was all this game was supposed to be about. That, and the game would rely on pure shock value if it were just that, giving us scissors right after the feather, for example.
We were given too many warnings (needle, his anxious comments, then the pain he expressed with hammer...) and enough rewards (raise in dollars for each click, making it easy to finish even without getting that tired), we could have pushed the morbid curiosity aside knowing it could hurt someone, but a lot of people simply couldn't. Is it really on author that they gave us the choice, when it was us that took it, when we didn't have to, when we had a perfectly good way to, maybe with more hassle, get what we need without hurting someone?
Why did we push Harvey still? Because he's fictional? But why do we dehumanize someone so easily, even if they share so many similar characteristics? Dehumanisation is the first measure you take to protect your psyche from the dissonance of hurting someone of your kind. So I'm pretty sure this game's meaning is to show our choices reflect us, the player. It means to make you ponder: he's not real, so I'm not a terrible person, right? It's just fiction, and if he wasn't real, I wouldn't have done that... But that takes us back to the setting. We are told we are desperate. We need the money for our operation. That gives us a sense of urgency, yes, but should urgency be used to justify going as far as seriously hurting someone?
I personally finished the game with the needle first. Tried to get back to the feather. Couldn't. Well just like Harvey tried to play it off as, acupuncture was the most I gave him. In my book, a person that tries to just spread good in the world shouldn't be punished for it, or taken advantage of.
And when it comes to your stance on fiction vs reality, I'll share my mindset as well: I think fiction reflects reality, and when fiction touches you deeply enough, it can impact you as a human being, forever altering your reality (after all, because of cognition, we all have our little separate realities. You can't say a blind person's way of perceiving the world is the same as someone with sight sense, no?)
Btw, have you ever heard of "Can your pet?" Somehow, because I read your comment, i remembered this experience... Giving this for me to play was the worst prank my friend could have ever played on me, especially since I was a kid then. At least here we had an outline that scissors are, well, scissors :/