I think this is a misleading ratio. It doesn't take into account for instance the fact that coffee production is mostly just planting, picking, roasting and grinding beans, while cocoa production is drastically more equipment and process intensive. You would expect to find a lot more people employed in the processing of cocoa than of coffee. Does that make cocoa better than coffee? Some would argue the opposite, that because coffee takes almost no equipment to process, that it is not creating pollution via factory processes and it is easier to get fair trade coffee to market than it is for cocoa.
The basic idea is sound, but, you must more directly compare a labour-intensive to a capital-intensive process. There is such a thing as capital intensity ratio in some theories of economics I think, and many economists believe that a low ratio is much more appropriate in developing nations. w:E. F. Schumacher had the concept w:intermediate technology to reflect this, which was a compromise between the "no tools, too much labour" of poor places, the "little highly skilled labour, way too many high tech tools employing a vast hierarchy of specialist" rule of rich places. A developing nation according to him had to replace US$1 worth of tools with US$10 and US$100 worth, not US$10,000 worth as in a modern US factory...