Dugout, file a claim with USPS. If they think they delivered to his house, they will investigate and could come after him. That's why you bought insurance. Posting pictures of his house, harassing his family and having your buddies threaten people will not be tolerated and can lead to you getting in trouble also. Not sure what he may have had in his personal life, but he has perfect feedback here and never had an issue. I understand you are frustrated as you trusted him based on this feedback, but please go about things the correct way. If there is anything I can do to help, please let me know, but use the facts and knowledge you have to get to the bottom. Police will get involved if USPS presses charges.
I don't know what really happened and not defending anyone here, but stuff is stolen from porches often. It seems to increase daily, hence why I have a camera that looks at my door. We have dealt with it numerous times over the years here, but how SS7 is handling it is on par with how we have handled here at SBF (minus the threats and name calling). It's on the seller to get the bat to the buyers hands. Insurance and delivery/signature confirmation is to protect yourself.