China, I'm not sure what to make of that 1957 study that you linked. The plants were grown entirely at the specified soil temps throughout their growth to maturity--which is not likely outdoors. In addition, they were grown in 1 gallon pots, in a greenhouse, between late October and late November (in Canada), and supplemented with artificial light. All pretty atypical growing conditions.
I agree that trying to grow them in winter, even without freezing, is pointless. But when they are transplanted outdoors in cool weather, they are likely to experience increasing average temp as each day passes. Since the plants are most vulnerable to pests when still very small, warmer soil temps would reduce that period. On the other hand, some tobacco pests are totally absent during the early season.
Bob