Ah, but not an exclusive two-hour primetime special...you would want to market it in advance, and my understanding is that the hackers would just release the decryption-information to everyone. Thus fewer people could profit by the release of the returns, making it less likely that to pay for release, and consequently less likely either of the two will pay, no?
Its also possible that the tax returns contain nothing interesting...if people were making a big deal about my returns AND they were normal-enough, I'd allow the controversy to fester so that I could slay it in one stroke by releasing my own returns days before the election.