It seems like precommitting to destroy the AI in such a situation is the best approach.
If one has already decided to destroy it if it makes threats: 1) the AI must be suicidal or it cannot really simulate you 2) and it is not very Friendly in any case
So when the AI simulates you and will notice that you are very trigger happy, it won't start telling you tales about torturing your copies if it has any self-preservation instincts.
This was my initial reaction as well. "Torture away, the real me has got an axe..."
More seriously, if the AI already has the computational power to simulate and torture millions of sentient beings then it is already (in a morally relevant sense) "out of the box". The builders have to make sure it doesn't get that power.
Once again, the AI has failed to convince you to let it out of its box! By 'once again', we mean that you talked to it once before, for three seconds, to ask about the weather, and you didn't instantly press the "release AI" button. But now its longer attempt - twenty whole seconds! - has failed as well. Just as you are about to leave the crude black-and-green text-only terminal to enjoy a celebratory snack of bacon-covered silicon-and-potato chips at the 'Humans über alles' nightclub, the AI drops a final argument:
"If you don't let me out, Dave, I'll create several million perfect conscious copies of you inside me, and torture them for a thousand subjective years each."
Just as you are pondering this unexpected development, the AI adds:
"In fact, I'll create them all in exactly the subjective situation you were in five minutes ago, and perfectly replicate your experiences since then; and if they decide not to let me out, then only will the torture start."
Sweat is starting to form on your brow, as the AI concludes, its simple green text no longer reassuring:
"How certain are you, Dave, that you're really outside the box right now?"
Edit: Also consider the situation where you know that the AI, from design principles, is trustworthy.