No, I'm saying it's not as simple as trusting the information-giver by dint of the fact that they claim to be a whistleblower. There's other ways the scenario could come about.
But it's not just the fact they claim to be a whistleblower. In Wikileaks' case, it's their track record. And in Murray's case, it's the perceived integrity that he has through blowing his career.

Can I be 100% certain of the integrity of either Wikileaks or Murray? Of course not, this isn't maths or physics we're talking about here. But to dismiss them based on paranoia relating to their intentions is to basically say I trust noone at all. That's a very depressing position to be quite honest.

There must be people out there who just want the world to be a better place. If I were in the position to expose government lies, I would do so without any interest in financial reward. Am I a special kind of person? I don't think so at all.