While it certainly might be the case that Bloomberg was simply duped, please consider that strong, unequivocal denials by no means mean those issuing them tell the truth - rather merely that they are VERY sure Bloomberg will never be able to prove they're lying. Or, alternatively, that they have an iron-clad excuse for lying if they ever get caught.
One is reminded of the old joke about an engineer, a theoretical physicist and a mathematician travelling together and seeing a black sheep. "Look, proof that black sheep do exist!" says the engineer. "No, it's only proof that at least one black sheep exists", counters the physicist. At which point the mathematician mutters "actually, this only proves that at least one sheep that is at least half black exists..."