Atheon doesn't have ki for one so that puts him in the same class as the androids, also the time travel talks about going light years in distance. Past Venus isn't "light years away" also goku aint smart enough to do the math required to make a specific jump back or forward (since he wouldn't know if he was in the past or future for that matter) and to top it off he knows nothing of the relic or oracles. He can't beat atheon if atheon teleports him. And he's got a high chance of being teleported since he loves to waste time trying to talk to his enemies before he actually tries to fight them even if they open with a barrage of attacks. He always starts on the defense unless it's a more formal fight like when he fought bills or in a tournament pretty much anywhere else in the series. Edit - Also sure goku has the powers of a god, but he doesn't know how to use everything on a whim. Cell said it best when he said "you can have all the power in the world but its useless if you can't catch the person you're trying to hit". In this case it'd just be Goku struggling to figure out what's going on. You're giving him way to much credit for being able to handle a situation of this magnitude completely on his own. Not to say the others would be much help since they too are also clueless about destinys' basic mechanics. The only people I can think of that would truely be able to assist him for a win would be bulma and Dr gero assuming they weren't immediately killed. And I only say them because they were easily two of the smartest people introduced in the show. King kai is good and many of the others would also qualify as being smart, but not technical smart, they know ki and energy. Non of that is at play in destiny.