The linked article does not give ANY details on exactly how Nunberg characterized individual politicians. All it mentions are a couple actors, and I don't know (or care) enough about their politics to kow if I'd agree.
And, you completely missed my point -- no one will ever "scientifically prove" bias or the lack thereof. A related point is that this should've been posted in politics, since this is a political question, not here.
So, I'll do my part and won't contribute any more to the making the Open Forum the second political forum.
Tony