I agree completely.
Yes, Evan has the right to financial privacy just like the rest of us, and it's completely his choice whether to reveal the extent of his holdings. I personally think he should, for several reasons:
a) There was a large instamine, which I believe was accidental. But given this mistake and the opportunity to gain numerous coins, I think a definitive answer would be helpful.
b) He is the founder, which puts him under additional scrutiny.
c) He is the lead developer and the true visionary behind the project. The credibility he has within the community is enormous, as is his influence.
d) The budget system could be manipulated, at least in theory, by somebody who has enough coins. The founder, whose "vote yes for this" easily counts for 500 votes, could, in combination with his own masternodes, have unusually strong influence over budget proposals.
These four factors, in my opinion, are reasons why he should chose to waive his right to privacy with respect to his Dash holdings. It's like the public figure exception to slander/libel law: in the U.S. at least, you can get away with saying a *lot* more about a celebrity or politician or other public figure than you could about a regular person. Why do you think TMZ still exists? =)
It's entirely Evan's decision though, and we must respect his right to privacy. If he chooses to reveal his holdings, that's great. If not, that's his right too.
P.S. Elbereth has mentioned before that Evan has about 270 MNs, which he presumably deduced from voting records. I apologize if posting that here is inappropriate, but it's already been deduced by another person from public blockchain records. In theory he could have more Dash that isn't in masternodes, or some of his MNs could be run for friends and family.
P.P.S. Fernando is absolutely right--even if Evan did tell us how much Dash he owned, we'd still have to take his word for it. But I think such a declaration would be designed to inform those who already believe in Dash, not to refute the trolls. It's like my dad said when I pointed out that padlocks could be easily cut, allowing criminals entry into our yard. He pointed out that locks aren't intended to keep the criminals out; they are intended to keep honest people honest.