From what I have read you hit this buck once and didn't get the job done.
If you asked your friend not to shoot this buck because you felt a moral responsibility to finish the job yourself, I can understand that.(May not agree but understand)
If you asked your friend not to shoot this buck because of some sort of antler envy then that is just plain chicken $&!t.
Only question I have is would you have reacted the same way if it was a doe?