What do you do with the mice that have been refused in a feed?
You don't refreeze 'em. You throw 'em away. Yeah, they're not pets to us, but they're pets to somebody.
Some might be breeders, that have MANY MANY animals, and don't have the yard space to bury them all - that doesn't mean they cared for the snake any less.
If it's a long-loved animal, that's a good few years old, sure, I wouldn't agree that would be a fitting end. But, if you've just had a dozen clutches hatched of 15-20 snakes each, and a few of 'em don't make it, what are you gonna do?