Plus, the advice to space Iodine away from vitamin C is based on what happens in vitro. Vitamin C reduces Iodine to Iodide in a glass of water. Often, what happens in the body is entirely different from what happens in isolation.
However, vitamin C is always in the blood stream at the same time as Iodine and iodide.
Since the body needs both forms of iodine, I suspect that the body re-oxidizes the vitamin C reduced Iodide back to iodine when needed for things like the breasts. I don't know the mechanism that would be used, but I bet it happens.
We know the thyroid oxidizes Iodide back to iodine in the process of making the thyroid hormones. I bet it happens in other tissues as well, when needed.