I think your explanation may be correct, but I don't understand why torture would be the intuitive answer even so. First, if I select torture, everyone in the universe gets tortured, which means I get tortured. If instead I select dust speck, I get a dust speck, which is vastly preferable. Second, I would prefer a universe with a bunch of me to one with just me, because I'm pretty awesome so more me is pretty much just better. Basically I just fail to see a downside to the dust speck scenario.
The downside to the dust speck scenario is that lots and lots and lots of you get dust-specked. But yes, I think the thought experiment is seriously impaired by the fact that the existence of more copies of you is likely a bigger deal than whether they get dust-specked.
Perhaps we can fix it, as follows: Omega has actually set up two toy universes, one with 3^^^^3 of you who may or may not get dust-specked, one with just one of you who may or may not get tortured. Now Omega tells you the same as in ike's original scenario, except that it's "everyone sharing your toy universe" who will be either tortured or dust-specked.
You're given the option to torture everyone in the universe, or inflict a dust speck on everyone in the universe. Either you are the only one in the universe, or there are 3^^^3 perfect copies of you (far enough apart that you will never meet.) In the latter case, all copies of you are chosen, and all make the same choice. (Edit: if they choose specks, each person gets one dust speck. This was not meant to be ambiguous.)
As it happens, a perfect and truthful predictor has declared that you will choose torture iff you are alone.
What do you do?
How does your answer change if the predictor made the copies of you conditional on their prediction?
How does your answer change if, in addition to that, you're told you are the original?