It's a good question, and one Vegeta really hadn't considered since while he act confident and arrogant about surpassing Goku, he knows he has a long way to go. But he knows one thing, "I have no intentions to try and kill him again." Those days were behind him, even with what happened when he had fallen under the Majin control had been more about defeating Goku, not killing him. "When the day comes, then it will be his turn to try and catch up."

As for his family, "Yes, I am sure neither of them would be happy if I was to kill the idiot, however both are more practical when it comes to actual threats." Much like himself. Goku always had a need to give someone a second change. Vegeta was not like that, even if he had been one of those who Goku had let live. There were just some people out there the universe is better without.