A bit harsh, since he took the animal promptly a vet, and was told it was a bacterial infection, not a burn!
I don't believe that the OP is an irresponsible owner--just one who didn't have a crucial piece of information, and then fell victim to a less than competent veterinarian, compounding the problem exponentially.
If the vet had said 'that looks like a burn', if the vet had asked any questions about the temperatures and husbandry, it would never have become so severe.