I really wish Bungie would do something and restore his characters somehow. I know they do not offer an official feature they so, they did promise such a feature but it still not available yet.
The problem that your kid was trying to glitch the game, and this could be why Bungie did not really support him in anyway.
Others here are saying that you as a parent should never allow him to play Destiny as it's rated ESRP T (PEGI 13) but I think Destiny is fine, it's much better than most games out there, and one of the least when it comes to violence. The real problem here was allowing your kid to talk and chat with strangers online, and later giving them access to Share Play. Streaming is also a really bad thing for such a young age.
I am sure he learned a lesson. I am glad that I have seen a few here willing to help him get back to what he had before. It could take time, but at least he will now always have people who support his back in Destiny, and probably make him even better than ever before!