He was/still is obsessed with Jonbenet, but got his info about her and her death, the same way he got the info about Polly. And he didn't start talking about Jonbenet until she'd been long dead. Yes, the man is a pervert, yes he IS into kiddie porn, and yes, he IS creepy, but there's NOTHING whatsoever to link him to Jonbenet's murder and a whole LOT of things to NOT link him with it.
I agree. It was actually the Polly Klaas thing that first raised my suspicion about him. He knew way too much about her for someone who DIDN'T kill her. Then, we find he's obsessed with JBR.