If he is INNOCENT what the heck does he have to be nervous about?
If he is Innocent why did he fail the first poly and then refuse another?
He backpeddles!
To be fair about him being nervous, he was on a national TV show talking about his missing child and presumably knew that viewers would be judging him. Even if he's 100% innocent, it would be a nervewracking situation IMO. Not to mention the studio audience - that alone would be enough to make many people incredibly nervous.
The poly, I still think his biggest mistake was saying he'd take it and then backing out. If he'd said no up front I wouldn't have thought it was a big deal, especially if he had a good reason such as being advised not to take it, or said he didn't trust the validity of polygraphs, something like that. I imagine Dr. Phil would've jumped all over those reasons, but it would've been a lot better than what MR ended up doing IMO. Freaking out that he had to go "right now," not feeling ok to take it when he got there, going back to the hotel and getting drunk, being mysteriously hung over and then explaining how little he had to drink (which IMO wouldn't make him all that sick the next day, even with the stress and lack of sleep). Individually each of these things can be explained given the situation, but when you combine them all it makes him look really, really bad IMO.
As to backpeddles, yes, I agree completely! I've lost track of how many times we've seen that. Thank goodness for archives so that we can go back and see the original story, and evolution over time.