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I don't know what "error: divide by zero" means in this context. Could you please clarify? (If you're suggesting that the problem is ill-posed under some decision theories because the question assumes that it is possible to make a choice but the oracle's ability to predict you means you cannot really choose, how doesn't that apply to the original problem?)
You want to figure out whether to do as the oracle asks or not. To do this, you would like to predict what will happen in each case. But you have no evidence concerning the case where you don't do as it asks, because so far everyone has obliged. So, e.g., Pr(something good happens | decline oracle's request) has Pr(decline oracle's request) in the denominator, and that's zero.