It is certainly a good idea, but it is not always easy to determine what people believe. On the present topic, they believe quite a variety of things, many of them extremely unclear. Why do you assume that if brains implemented soul-code as you describe, someone would think it was the brain that was them, rather than the soul-code? The view that brains implement soul-code and that the soul-code is the real person sounds to me like a not implausible interpretation of much of what Plato says about souls.