I believe that the vast majority of people in the dust speck thought experiment would be very willing to endure the collision of the dust speck, if only to play a small role in saving a man from 50 years of torture. I would choose the dust specks on the behalf of those hurt by the dust specks, as I can be very close to certain that most of them would consent to it.

A counterargument might be that, since 3^^^3 is such a vast number, the collective pain of the small fraction of people who would not consent to the dust speck still multiplies to be far larger than the pain that the man being tortured would endure. Thus, I would most likely be making a nonconsensual tradeoff in favor of pain. However, I do not value the comfort of those that would condemn a man to 50 years of torture in order to alleviate a moment's mild discomfort, so 100% of the people whose lack of pain I value would willingly trade it over.

If someone can sour that argument for my mind, I'll concede that I prefer the torture.