You could,
of course, remove the rust (I would not use steel wool, the particles which you will inevitably miss could cause some interesting fireworks) but you can't recoat with epoxy because of the heat and all the high heat paints I've ever seen definitely are not for use in a baking oven for food.
However, if the metal is still sound under the rust, then I don't see why it shouldn't continue to work.
If the rust has eaten through, I'd discharge the capacitor safely, gut it and keep the parts. Those were very common ovens over many years and you're bound to find another one sooner rather than later.
