They aren't sure why yet, but there's supposed to be some follow up work to figure it out.
I've heard of that, that organic tomatoes for instance have something like double the lycopene; the suggestion is that tomatoes produce lycopene as a response either to nutrient stress or as a response to predation. And it may just be that they're using cultivars that naturally have more lycopene, simply because they're hardier.
You see that a lot in organic crops; they're usually cultivars selected for hardiness, and a lot of that hardiness comes from natural pesticides.
But they're no less dangerous from being "natural." Recently there was a recall of organic celery because it was so high in natural pesticides that people were getting rashes just from handling it. At any rate, you could simply buy lycopene supplements for what you'd wind up spending on organic fruit.