I know there are time restraint for things that happen in game but you still have to account for if atheon decides to change it up. Gokus stuff is all improv cause he's never been there, we don't know how atheon would react. He might teleport him faster, slower, or not at all. He does stand a chance to kill him outright but there aren't many times goku immediately charges in headlong at full power. He usually tries to talk to the enemy first or measure how strong he thinks they are. Those few seconds he kills trying to make contact by talking and dodging shots is enough for atheons timer to drop for him to be teleported. He kicked friezas goons asses left and right but he stopped to talk to the big man before the showdown. No matter what powerlevel he's at he always chats it up a bit. And as cocky as he can get I'm betting he might talk shit about how slow he is or shoots while dodgeing and get himself teleported.