Will Falconer, DVM Moderator
Yes, Autumn, the short sweet answer is: if your vet isn't on board with this 16 year old indoor cat having no need for another rabies shot, he's FIRED. And you tell him why, in no uncertain terms. Then, proceed to find a more knowledgeable and sympathetic vet who will provide this service without putting your old guy at risk.
This may also be all he needs. If you see betterment in a month of this, carry on, you may not need dental work at all, though some cats really do need to get teeth extracted, as they've got an autoimmune issue going on in their mouths. All the best to you both.