The address belongs to R & A International Logistics, Inc. They are a freight forwarder. The address may or may not be legitimate for the "son" but it's irrelevant, as others have said, if it's not the address that paypal has on file for that buyer, and you would lose any not received claim.
Of course, the buyer can simply add that address to their paypal account and then repay using that address, and it would all be good, but I get the feeling here that the buyer would not do that, but you could ask them that and then gauge their sincerity by their response.
What is Proof of Shipment?
"The recipient’s address, showing at least the city and state, or city and country, or zip/postal code (or international equivalent). The address information on your shipping receipt must match the address on the Transaction Details page."
This is a common scam, although I am not saying it is here, but often seasoned scamming buyers switch the address on unsuspecting sellers and then claim they never received it and the seller has no proof it was delivered to their address on file, because it wasn't. It is often pulled on new sellers with 0 feedback like you, selling high-priced items.
Also, if you ever get an email saying that you have been paid and OK to ship, never click on any links and, ALWAYS check your paypal account first to see officially; There are a lot of spoofed paypal emails doing this.
