I just don't understand WHAT is it that he's expecting to confirm that Misty is hiding something. I mean, he's already suspicious and things that point to Misty hiding something are piling up. It's not like she's his devoted, deeply religious wife of 30 years who quite beyond all suspicion because she is bedbound and could never hurt a fly even if she wanted to which she doesn't, and he just can't believe she'd do anything. No, he already suspects her so why is it so difficult to convince him?
I could perhaps buy his being suspicious of polygraphs if it was only the polygraphs but there are the inconsistencies in her story and it's been said that he knows first hand that things at the home weren't the way they should have been if Misty's story was true, and LE must have given him some inkling of the problems in Misty's account, and the media have pointed out reasons to believe that Misty is hiding something over and over again.
What is it going to take? Is he suspicious of her and trying to get to the bottom of it or is he a blind, naively trusting husband because he can't easily be both at the same time?