No, that just shows he has a basic understanding the how our criminal justice system works. Ms. Wilbanks wasn't "found" by the FBI or any other law enforcement agency, she turned herself in. Whether he was innocent or guilty John Mason was the main suspect from the moment she was reported missing, and nothing he could do would change that. It would have been more far more irresponsible of him to meet with the authorities without an attorney. One misspoken word or "indeterminate" polygraph result would have put the press into a frenzy that would have effectively ended the search for Ms. Wilbanks.
No one has ever been "cleared" from suspicion by a polygraph test or by being interrogated without an attorney present. Remember this is someone close to you ever goes missing.
Regarding your #302...I find it hard to believe that if you knew you were completely innocent that you would hesitate to strap a lie-detector on.