If you accused the breeder of selling you a sick snake, it would explain any rude behavior, but if you just brought up the animal's illness/death and the breeder became defensive without asking about necropsy or pictures or husbandry etc, then it's a red flag about the breeder...

Either way, I'd also save up an emergency vet fund and totally disinfect everything before you get another animal. There's no way to guess what caused the death without a necropsy.