Well I would like to say what has happened with Jose our Mexican Black King.....
When we got him he had been fed live for 4 years. He has lots of tiny scars.
Anyways, for the first 4 months or so he only wanted live. No problem, because I could sit and watch him eat. One day he snatched a mouse with as much power as a kingsnake can, and while in the coils the mouse reached out and bit him right on his side.
I was *right* there. There was no way I could do anything at all. I couldn't uncoil him, and I couldn't take his mouth off its butt, and of course the bite to his side didn't make him let go at all. Luckily a few seconds later he moved position, and coiled tigher and tigher and it stopped biting.
But he could have lost an eye, had a serious wound, or any number of things and I was sitting right there. So I don't fed live anymore even when I am practically in the cage with them!!!!
Also tell him snakes can get exersice if you take them out and handle them! You don't have to endanger the life of the snake because he may miss out on 5-60 seconds of exercise.
And killing live in nature VS killing in a cage??? How can he even compare? The cage automatically gives the prey no chance of escape, they start panicking even more when they cannot run. We are talking about snakes who this guy himself has decided to keep in captivity using all captive methods, yet he tried to argue its "natural" and "like the wild" ??? Doesn't make sense, and I would tell him so.
I hope you can convince him!!!!!