Solar and wind require a huge geographic footprint to generate significant energy. Because of this constraint, the cost of wind and solar is almost entirely opportunity cost, not the mere accounting cost of producing an extra panel/turbine. The basic problem is twofold: First, as you keep adding solar/wind capacity, you inevitably get diminishing returns from worse wind/sunshine conditions, so additional installation is less productive. (Think about solar panels in valleys or windmills in low-wind areas.) Second, as wind and solar cannibalize land area to provide energy, the price of that land increases substantially as other uses are displaced. For example, let's say that a country had to displace 40% of its productive arable land in order to install wind & solar. Then the price of its farmland would skyrocket as the country continued to deploy wind & solar. In both cases, solar and wind become much more expensive per deployed panel than simply the cost per panel, which is indeed pretty inexpensive. FWIW, the article attempts to make this point, but it frankly isn't very well written, and so the point is a bit hard to understand.

As to your point about countries situated for nuclear vs wind+solar, what do you mean? Do you have any metrics? If I were to guess, wind and solar are extremely sensitive to the geography of a country (including physical and political-economic); I'd guess nuclear is mildly sensitive to political geography. Splitting the atom is not significantly harder in Indonesia or Peru than it is in France. The fact that much of French land area is rural might make nuclear marginally more useful there than in a place like e.g. Germany or the UK, with several major cities dotted across the relatively densely populated landscape. (Based on this inference, I'd imagine that the US, China, Canada and Russia would be the top four countries for nuclear, and Monaco or Luxembourg might be the worst?)