However, it's not just Andrew Leatherbarrow who thinks so. All it takes is a simple Google search and you'll find reputable research papers hosted by the IAEA whose primary conclusion is that the accident could have been much worse. Here's one example: https://inis.iaea.org/search/search.aspx?orig_q=RN:18009127
I did not say that the IAEA paper was about molten rods hitting the coolant water. There is more than one way that Chernobyl could have been much much worse. According to the paper, different wind and rainfall could have made the disaster 200-400x worse in terms of radiation consequences to humans. To say that is significantly worse would be an understatement.
> Popular books have the incentive to garner sales - often through dramatization - not report accurate findings.
It seems like you've made up your mind and no amount of evidence to the contrary will change it. I don't think I'll bother to continue participating in this line of discussion.
> That water was drained, precisely because of concerns that it would melt down and come into contact with water.
Even if the concrete base under the reactor was breached, the water underneath had been drained. In retrospect this was unnecessary, but it added another layer of precaution.
Furthermore, what makes you think a potential explosion after coming into contact with water would be "massively" worse than the original reactor explosion? In case you aren't aware, the RBMK-1000 was a water cooled reactor. The explosion happened because the temperatures inside became so high that the pressure vessel ruptured. By comparison, the contact with the water beneath the reactor hall would not be trapped in a pressure vessel and wouldn't result generate such pressure.
What actually produced the most amount of nuclear contamination was the period of time when the fuel rods were exposed to atmosphere and burned. This put large amounts of contaminants - radioactive smoke, essentially - into the atmopshere.