Serapy, Vost's theory doesn't hold. I disproved it with the use of mathematics and statistics. As much as you can argue on factual arguments and still get very likely or very unlikely conclusions from them, you cannot argue against maths. It holds - always. So, you cannot use Vost's argument as an example about why R=U, because it is fundamentally flawed.

And the flaw is inherent in all R=U arguments. Rinoa cannot exist in Ultimecia's time. The argument had its merits, until Square-Enix explicitly stated that sorceress' have normal human life spans. That is a fundamental flaw, and Vost's argument to try negate this flaw is itself fundamentally flawed.

So, when an idea is shown to be fundamentally flawed, it is very lucky to have it written down as very unlikely in the FAQ.