Logically, what you say may be true. But species and subspecies and such are determined by genetics, and ruderalis could simply be sativa with a deviant gene or something. I'll let the geneticists figure it out. Ashkenazi Jews tend to have some genetic diseases (from inbreeding in the distant past) and the average Ashkenazi Jew appears to be significantly smarter than your average non-Ashkenazi (they are the smartest ethnic group in the world), but that doesn't mean they're a different species; they're still homo sapiens. Ruderalis may have a similar genetic deviancy from normal sativa, but that doesn't necessarily make it a different species.