So you're saying you'd feel better if Pirate told you some story rather than tell you nothing at all? "Lie to me, don't just say nothing"
Well, you put it that way, it sounds silly, but yes, essentially. At least go through the motions of making a believable mechanism that spits out the cash. Of course, that opens up the mechanism to being scrutinized, and it would take a clever Mechanical Turk indeed to fool everyone. Thus why a black box arouses more suspicion than one I can see into.
I agree that while on the surface more information allows the truth of a lie to become more apparent, human psychology still works against it. Pirate has told many stories already, and that's what very few people are scrutinizing. They're wonderful stories, though, which make people feel good to believe. Most people don't realize just how much control their emotions have on their decision making.
It will possibly help those people who are smart (or emotionless) enough to even bother scrutinizing, but the vast majority of people who, for example, still take the bible literally or the existence of Gods seriously, it's more important to be part of the story than it is being right. Our brains are wired this way, perhaps because there is safety in numbers.
The people who would scrutinize the information / story given, are the same people that wouldn't invest in a black box now due to the insane unpredictability / gamble of it. Do you invest with pirate now? Would you invest more with more information? Are you looking for justification to invest because you want to believe it's possible to earn this much?