You seriously do not watch DBZ do you. If you did you would understand what Goku is CAPABLE of. If he wants to destroy Atheon and the vault all he has to do is give the Big Bang Kamehameha wave x100 and everything would be go e fast than you can say teleport. Goku might not want to destroy a planet because he is a hero but what makes you think that he is not powerful enough go do it? All he has to do is flick his wrist and the planet would be gone. Also there is nothing in Destiny that can move faster than the speed of light and that is just about everyone in show. Everyone in that show can move at the speed of light. Heck even Krillan can destroy Atheon and his army and he is human. Trust me, there is no beating Goku and if you knew anything about him is he loves to fight and always wants a challenge. Why do you think he fought Beerus the Destroyer? Also you neglect the fact that if somehow Goku does die, his friends would bring him back with the Dragonballs and if you watched the show you would know he comes back 2 as strong as before every single time. There is no limit to Gokus power.