My guess that is only for protecting varieties, but not all rattlesnakes.
Yes, machetes work fine. In my herp class at Texas A&M, James Dixon liked to start off classes with stories of a bizarre nature as they pertained to herps, or stupid human tricks as pertained to by herps. Some of his favorite were the accounts of folks doing things like using a skick, rake, hoe, or machete to try to kill a snake and getting bitten in the process. In many cases, the bite was either a second bite on the person or a first bite on a buddy who felt it necessary to have the snake to take to the hospital so that the right anti-venom could be administered. The really funny part was that often the first bite was a dry bite and so the original injury was nothing a bandaid wouldn't fix, but the second bite, either to the same person or the idiot helper, was full of venom and that was the bite that caused all the trouble.
FYI, there are only two types of indigenous snake venon here in the US. Rattlesnakes, copperheads, water mocasins all inject the same hematoxin. Coral snakes inject a neuraltoxin. If you were invenomated by a snake that was not red, black, and yellow, then you ended up with a hematoxin. The question is just how much did you get? Copperheads and water mocasins physically hold less than rattlesnakes, but all have the ability to limit the amount of venom released. Don't be fooled into believing that their little BB-sized brains do higher math. They don't engage in a complex decision tree on how much to give you when they bite based on their current needs, perceived fear, and how big you are. They just bite. If they are really scared, they will give you as much as they can. If they aren't really scared, you may get a dry bite.
