If anyone in the organization can frustrate the purposes of the organization by unauthorized disclosure, that would constitute a veto under any real definition of the word. You can have every system in the world to address their grievances but sometimes, there are just nuts who cannot be placated. It is naive that loyalty is the only thing that works. But then you acknowledge that by saying that you have to chase down the "occasional psycho". That kills your entire thesis; loyalty is not enough.
That's why there are coercive laws against espionage and the like. The honor system is really just not going to work. You use data control measures in conjunction with investigations, audits, lie detector tests, legal action against leakers, etc. It's nuts to just say that you have to make everyone happy because you admitted that you cannot. How do you detect the occasional psycho and stop him or her from leaking unless you have data control systems and routine audits to detect them? Or unless you have laws to punish them to persuade them from stopping?
TL;DR: Honor or loyalty isn't enough; you need all of the above.