I understand the point you are making, but I don't think I am an in total agreement with you.
Yes, you are correct that this will protect the flamethrowers, but it also protects the legitimate whistle blowers and those are the ones I care far more about.
'Child abuser' is one of the nicer things I have been called on various blogs and forums, including Free Republic, and I've never abused a child in my life - but guess what? I don't want the pathetic people saying such things to be outed - I just prove them wrong by my own life and my own statements.
If we can't compare people we've never met to Hitler, what's the point of posting on a forum?
Nothing "protects legitimate whistle blowers" - unless they happen to be democrats or liberals. Whistle blowers who are conservatives DO NOT GET PROTECTED.
That's why this isn't a "free speech" issue - this is legitimizing SLANDER issue - and not being held accountable for false charges against a person.