It would not take a genius to know that everyone is against you which this is all about. Goku vs the whole Destiny Universe. If the universe is against you, and you have the power to destroy said universe, you would not fool around and act stupid. Goku will know that he is not in his DBZ universe and everyone is against him. It's Light + Darkness plus everything in Destiny vs a single person. Goku will go all out for sure. If you were given Goku's set of powers and you suddenly ended up in a similar scenario, would you get chatty and fool around? Nope. You would start blowing things up until they give up trying to kill you.