Earlier quoted context omitted.
Back then, it affected everyone in two ways, which were the things Greenpeace campaigned against: nuclear weapons, especially overland testing, and dumping waste at sea. Chernobyl took out Welsh farming for years, and in a few places decades, because it spread a thin layer of bioaccumulative poison over the whole of Europe.
Neither of these have anything to do with running a well-regulated nuclear power program. Chernobyl happened because of the apathy and incompetence endemic to any Marxist-Leninist system, not because a modern democratic state is incapable of regulating the nuclear power industry. Know what else spreads a thin layer of poison over the whole of the world? Coal power.
Democracy just as lazy and apathetic is whatever the USSR counts as; the point of capitalism (which is different to democracy) redirect the laziness into something more productive — this works to an extent, but depends on competition which is greatly reduced in the case of nuclear reactors.
That it's a different axis than democracy-communism is also why the not-at-all-democratic military reactors around the world seem to be doing fine.