There are legal avenues for whistleblowing through IGs and/or Congress.

You can't write a law that gives journalists special access to classified information and giving them arbitrary information is ok, how would that even work? (That's without getting in to the complications of defining 'journalist').

If you wanted to argue that leaking information of illegal government activity in certain circumstances is an affirmative defense I could possibly get behind that, the devil would be in the details.