"He's not under any compulsion to give a password is he? They had the phone, nothing forced the authorities to trust anything he said....they could have tried forensics like they'd do if they had a safe and tried a safecracker to get in if the suspect didn't want to give the combination."
This is the interesting part to me. He definitely could not be compelled to give them his password (legally). So the fact he offered them a password could be covered under freedom of speech. Depending on what was said, lying to the police can be a crime, especially when it could be considered obstruction of justice. Did they just ask for a PIN and he provided a PIN? Did he say the PIN would unlock the device when it would actually wipe it? It could also show he intended to destroy anything on the device, and while they can't prove there was anything incriminating on the device, it could still be considered evidence as it was data for an investigation. There are a lot of different paths I can see this going down.