I don't think they did this for fear of being bitten, it was likely witchcraft. (voodoo). Snakes are a huge part of many cult-type ideas like these. Also, I have to say, I don't agree that it's okay, by any means, to do this to a rattlesnake or another animal. If the animal bites, why don't you just let it be instead of going through the danger of capturing it and seriously injuring it? Euthanizing it instead would be more appropriate.