why didn't goku just go alone to kill Dabura and others before buu was reassurected? he was dead anyways, he couldn't just die again could he?

I'm on episode 221 dbz, maybe my question will be answered in next episodes and i just haven't seen enough but i can't stop thinking about it,like to the point where it annoys me. Goku can't die when he is already dead, why not use the last hours of his time on earth to murder em? are there some rules that I'm not aware of.. like dead people cant do that or smth