Ignore anything you hear from Jim Hall. He is now acting on behalf of the ambulance-chasing Nolan Law Firm, and seems to have no interest besides making the potential jury pool prejudiced against as many possible deep-pocketed defendants as possible. He does not speak for the NTSB, and should not be using his former NTSB credentials to make it seem like he is an impartial expert while he is in the business of suing anyone and everyone who might have to cough up when a plane crashes.
He's off my XMas list, too.
Oh, and by the way, I'd be shocked, extremely shocked, if 3407 actually crashed due to the effects of airframe icing, wing or tail.