The point is that without arbitrarily drawing the specks/torture boundary somewhere between x stabbed toes and x+epsilon stabbed toes the suggested utility function does not work.
Hm, how can I help you see why I don't think this is a problem?
How about this. The following two sentences contain exactly the same content to me:
"Without arbitrarily drawing the specks/torture boundary somewhere, the suggested utility function does not work."
"Without drawing the specks/torture boundary somewhere, the suggested utility function does not work."
Why? Because morality is already arbitrary. Every element is arbitrary. The question is not "can we tolerate an arbitrary boundary," but "should this boundary be here or not?"
Admitting to being wrong isn't easy, but it's something we want to encourage.
So ... were you convinced by someone's arguments lately? Did you realize a heated disagreement was actually a misunderstanding? Here's the place to talk about it!