Freezing is not a humane method of killing a reptile, nor is CO2. If you don't have it in you to destroy the brain of a hatchling that's deformed enough to likely be experiencing excruciating pain right out of the egg, you really shouldn't be breeding them. I doubt many people have access to lethal injection, so we'll pretend that's off the table. Lots of people think 'oohhh ill put this snake in with this snake and make a pretty pokemon.' I don't mean to belittle our hobby, but there is a HUGE amount of that kind of behavior going on. You put the snake in the freezer because you 'don't have it in you' and subject it to unimaginable pain and trauma that way. That is not fair to the animal you forced into the world. That is not ethical animal breeder behavior and you should stick to animal keeping and not breeding.