Without more information, holding the position that _no_ AI could convince you let it out requires a huge amount of evidence comparable to the huge amount of possible AI's, even if the space of possibility is then restricted by a text only interface. This logic reminds me of the discussion in logical positivism of how negative existential claims are not verifiable.

I have a feeling that if the loser of the AI Box experiment were forced to pay thousands of dollars, you would find yourself losing more often. Still it is interesting to consider whether this extra condition takes the experiment closer to what is supposed to be simulated or the opposite.