UPS accepts packages containing firearms, as defined by Title 18, Chapter 44, and Title 26, Chapter 53 of the United States Code, for transportation from and between licensed importers, licensed manufacturers, licensed dealers, and licensed collectors, as defined in Title 18, Chapter 44 of the United States Code
I'm pretty sure neither of us qualifies as a licensed importer, manufacturer, or collector.
He's just going to ship the gun in parts in separate shipments, since it says that it's ok to ship gun PARTS as long as they can't be assembled to form a firearm