If he feels ready, and you provide any document he needs, as well as a source of funds, let him do it IMO. From your description, he seems ready, especially if he would not have to leave any airport on his own.
My friends regularly sent their two kids (together for mutual support, and both expressing comfort with doing the trip) to their grandparents in Brazil, from the time they were 5 and 6 respectively (and more on their own by the kids' reports than 'services' for minors would lead you to believe) and they have grown into very resourceful young people because of the experience.