If "built" refers to building the AI itself rather than the AI building a torture simulator, then refusing to be blackmailed doesn't prevent the AI from being built. The building of the AI, and the AI's deduction that it should precommit to torture, are two separate events. It is plausible (though not necessarily true) that refusing to be blackmailed acausally prevents the AI from becoming a torture AI, but it cannot prevent the AI from existing at all. How could it?
It is plausible (though not necessarily true) that refusing to be blackmailed acausally prevents the AI from becoming a torture AI, but it cannot prevent the AI from existing at all. How could it?
In this case "be blackmailed" means "contribute to creating the damn AI". That's the entire point. If enough people do contribute to creating it then those that did not contribute get punished. The (hypothetical) AI is acausally creating itself by punishing those that don't contribute to creating it. If nobody does then nobody gets punished.
Todays xkcd
I guess there'll be a fair bit of traffic coming from people looking it up?