Unless Couric thought the notion had credibility she would never have raised it. Sneaking in qualifiers like "possibly" or "some say" is nothing more than a technique Katie uses to give herself some cover when expressing her own opinions.
I'm guessing you didn't see the actual interview. If you had, I don't think you'd have any doubt that she was expressing her personal viewpoint and making a very serious accusation.
I am well aware. Guess I should have put a sarcasm tag on my post. Thought it was obvious.