Chernobyl was not a worst-case scenario, it is just the worst scenario that has happened so far. If it hadn't been handled by humans sacrificing their lives to stop the chain of events, it could have been much, much worse. Had the fire continued it could indeed have been a "wasteland" scenario.
The site you recommend makes claims about safety that are logically broken. Things are not safe based on what has happened so far, they are safe or unsafe based on what could happen in the future. Surely you realize this.
The claim this site makes is equivalent to saying that a gun is safe if it hasn't been used yet. I frankly find it to be a very dishonest argument, it seems designed to mislead rather than enlighten.