How could you feed that sweet little rat to a mean snake hmmm?
Tell him the same way that sweet little rat would happily eat him if it had to. Like it or hate it, deal with it or don't deal with it, it is nature.
All animals eat living things to survive. Even the grass that the cows who make those tasty steaks is alive, so where do you draw the line?
If the animals butchered to feed him is a different story, what about the animals his cat or dog catches and eats? What about the helpless fly that spider in the corner of his ceiling just bit and paralyzed and then injected with enzymes to slowly dissolve it's insides while it's still alive? Or the crickets that cute lizard who lives under his porch eats whole? What about the worms he slowly drowns to catch a fish he will chop apart while it's still alive to fry for supper? Does he weep over these things?
If not, then he should. How is there one bit of difference between you feeding your snake a rat to help it survive any different than any of these other things ? If he feels you are being cruel, then by turn so is he. If he wants you to stop, then by all accounts, he should get rid of his dog or cat, spray the house for spiders, run the lizard off and never fish again. You cannot single out one person or action as cruel and deny the reality of the rest.
Gale