Well, George, your certainly not shy of making controversial statements, I'll grant you that much.
I'd have to say that given the right lathe, I don't see any reason why somebody could not turn left-handed. The positions of headstock and tailstock would need to be reversed, but that is feasible on a fair few models.
Having said that, I have noticed for myself that I really need to be ambidextrous to get the best results. There are some cuts that just work a whole lot better (even in a right-handed setup) when the left hand guides the tool and the right hand is on the toolpost.
Being left-handed is not a choice. I remember the days when lefties were forced to write with their right hands in school, and the results ranged from hilarious to disastrous. Having tried writing with my left, I can tell you it is awkward in the extreme if cannot use your natural disposition.
Tim may not be an extreme case, or maybe he has a natural ambidextrous capability. Overall, I think, we (as a community) need to consider how we can accommodate lefties better.