There's also a rather large amount of anti-nuclear hysteria in there.
All plants would have 'burned or melted down'? Sure, apart from the 100% of plants that weren't in the middle of a dangerous test with all the safety systems turned off at the exact moment that the operators disappeared.
The rest would just go cold and sit there (pretty safely, baring an earthquake) until erosion broke down the concrete containment building.
"Immediately: None of these events would be judged positively or negatively based on human ethics."