Fair enough, and I don't know your background but I'm not even a lawyer, but I read the tax laws pretty regularly.... I'm a geek in some ways and just enjoy reading about questions like these and was throwing in my pretty uninformed 2 cents.
eace
I'll just say that my own personal opinion is the standard of candidates releasing their returns is IMO an excellent thing, because I believe we have a right to know where a candidate makes his or her money. It will almost certainly influence a lot of decisions if, for example, some industry paid a candidate $10 million to sit on a board, or be a nominal VP of something. Disclosure either makes that a non-starter because someone contemplating running can't bear the heat of disclosing it, or if they do get that kind of deal, the public should know, especially in this era where $10 million or $50 million is peanuts to the big boys.
So it worries me that Trump said no, and it didn't cost him, and I worry the standard has been shattered. Darkness in politics is IMO corrosive and sunlight a great antidote to a lot of problems so the more the better as long as the disclosures are reasonable and the history of the requirement in the past few decades, with every candidate doing it, indicates it is reasonable as I see it.