I can understand if he was stressed after the show. It started out OK, but after Mark started talking in (what I consider) circles, it did go south. IMO,if he didn't want to take the test, he shouldn't have taken the test, but he should have just said so. The words "I don't think I can take the polygraph under these conditions." aren't so hard to say, and they would be understandable. Especially if he were to say, "Could I come back in a week by myself to take the test?"
For myself, I could not imagine NOT taking the test. And I am a person who failed the question "Is your name....?" and it WAS my name--they had given me five baseline question, and that one was supposed to be the sixth and the indicator jumped all over the place. I had to come back the next day, when I passed knowing my name. I passed the rest, too, BTW.