They're referring to the fact that the reactor meltdown at Fukushima is the newest addition to the list of incidents that 'prove' that nuclear fission energy is

They're referring to the fact that the reactor meltdown at Fukushima is the newest addition to the list of incidents that 'prove' that nuclear fission energy is bad and should be banned. They're glad that the reactor meltdown is juxtaposed to the real disaster (in terms of human life lost) namely the earthquake and the tsunami itself. So that people place the reactor meltdown in the correct category: 'bad, but not a terrible earth-shattering disaster of epic proportions'.