If it remains in the tub and kills the mites on your snakes, it is not much different then using the Nix solution. But by all means use whichever. Personally, I think a product designed to use on humans has more testing than a product used on snakes. In other words, I bet it is likely less toxic. None the less, neither are great if they can be avoided
Good luck, and I hope your snakes are doing well.