If he is not willing to practice ethical hunting, including passing up on less than perfect shots for now, then he does need to quit... in my humble opinion.

Yes it happens to most of us, something all of us regret. But from what I' m reading in this discussion board, the people here have gone past that, tried to learn more, and practice harder to make those better shots, better decisions, and improve their tracking. I know I have and will continue to.

Hopefully he can turn that aching feeling into a powerful ally to become a better hunter.

In my humble non-expert opinion.