It's unreasonable to believe that biases don't exist - we all have them. And as much as we try to keep our biases out of our professional lives, there's always a chance they'll slip through. That doesn't mean you settle for that; it means you hold your beliefs to the fire, challenge them, and still see if they hold weight.
Now, some people don't change their minds about anything. They just stick to their opinions, and are more than content to sit back at a distance and pick apart the comments of others to make themselves feel morally and intellectually superior. And that's their prerogative.
But there are some things that are just fundamentally wrong, no matter what your bias is. You can call a duck-billed platypus a duck rat all day but that doesn't change the fact it's a duck-billed platypus.
All the liberal or conservative bias in the world doesn't change the fact that she's, time and again, saying things that are blatantly untrue on the air while just constantly deflecting valid points.