I don't care either way about the snake dying, personally I don't like snakes; had a bad expirience with a rattler as a kid and now they scare the **** out of me, but I don't condone killing them for the sake of killing them. However, I fail to see how the snake getting the baby chickens is nessicarily his (or his family's) fault.
I mean if they did something stupid like leaving the door to the coop open or just letting the chickens run loose in the barn or whatever, yeah, it would be their fault. But if a snake just somehow got into the chicken coop, its nobody's fault, just one of those things that happens. And its not like the snakes gonna be missed, so no problems with it dying.
Snakes gotta eat so its not the snakes fault, and if they did everything reasonable to keep the chickens safe, its not their fault either. Just saying, the 'if you can't keep your chickens safe' comment seemed unessecary, I mean are they supposed to take turns guarding the chicken coop 24/7?