>>544586239
>Goku was trying not to blow up the Earth.
He's had fights like that before, he knows what to do. During the fight Buu constantly shows off and Goku is shocked at how good he is.

>He had a pretty decent advantage on Kid Buu
He did not. Goku even comments he's trying what he can to kill Buu and hasn't had the chance to do it, and Buu isn't even taking the battle seriously.

>Since he's using a dead body in that fact I'm pretty confident he could've gone all out and taken him out.
I seriously don't see that, the fight was short, Goku didn't do much during it, and still used up most of his time on Earth. Any serious battle would use even more, and I doubt Goku would be able to pull it off.

>>544586306
Yeah. Goku even starts the fight with Kid Buu with a kamehameha, and used it again at a later point, both of which destroyed a lot of Buu's body, but it wasn't nearly enough. I don't see a dead body making any difference besides making him tire less.