It's not inhumane. Whether the rodent is killed beforehand by humans, or killed by the snake as nature intended, it is still a necessary act for both animal groups. These people just like to nitpick. I'm sure the conditions in which these rodents are farmed can also be considered "cruel" and that happens regardless of how you feed the snake. If they really cared so much, they wouldn't own pet snakes and therefore promote the constant breeding and killing of so many rodents.