To use the old bullshit that everyone trots out whenever secrecy or privacy is mentioned.
It may be that there is nothing there but we won't know unless it is investigated properly.
You could claim that this, like the tax release and Trump's overall buffoonery, are diversionary tactics to dilute opposition to policies like tax cuts for the rich, healthcare, environmental cuts but he does not seem that devious. Or he is that smart and excellent at playing an arrogant and naive liar.
As long as you recognize that it is, in fact, bullshit. :p
I'm very pro-privacy when it comes to private citizens, and the idea that's weakened our Fifth Amendment, from the late Justice Scalia - "If you are innocent, you should have nothing to hide" - is absolute garbage, and should be thrown away and left to rot. That said, I do think there's a difference when it comes to public officials who can impact policy and legislation, and whether they have a conflict of interest that would impact their decision-making and bias. Let's not pretend Trump is the only one who has any such conflict, as I'm sure the majority of legislators at both federal and state levels have tons of conflicts all the time that are rarely, if ever, brought up.
In an ideal world, government would be limited enough so that it would be difficult for these conflicts to come into play; although the president having foreign ties would probably be an issue even in that situation. And in the current situation, it may be that everything is above board, but Trump and/or his Russian business partners may have reason to keep things quiet that have nothing to do with legality. That would still probably create a conflict of interest, regardless, though.