You're attributing that he's scared, when he is simply exercising his right to conduct his personal business privately.

This would be a perfectly reasonable argument for almost anyone in the world, but most certainly not for Donald Trump due to his position and his track record of statements on public record on Twitter, of all places.

By your example, I could argue that you posting publicly here in HN eliminates your right to keep your personal finances private.

You cannot authorize a different standard of law to a person without invalidating that law.