That's why the results of the study shouldn't be surprising. eg. Fair trade coffee is "a good thing" because it helps poor farmers, not because it keeps you awake better. Organic shouldn't be better as food.
What is surprising is that people who eat organic/home grown veg would be expected to be more health conscious, eat better diets, not smoke/drink, etc.
So either they did a really good job of correcting for this - ie found yoga+healthy eating+exercise nuts who nevertheless only ate supermarket veg.
Or the whole study was too small/short to show any effect.
Or those who claimed that they always ate organic were lying.