I don't fault him either for being careful. If due to nervousness or equipment inaccuracy his lie detector test results had cast any doubt on him, his life would have become more of a nightmare than it was already.
This thread is beginning to sound like the Salem Witch Hunts.
Not only that, but a true sociopath can often ace a polygraph, while someone who's not guilty, just nervous and scared, can fail them. I think he had good advice, probably from his father, an ex-judge. After Scott Peterson and Mark Hacking, I don't blame anyone for suspecting him--and I don't blame him for protecting himself. That ditzy would-be bride of his might have just left him to twist in the wind.