If the dramatisation of the actions in the immediate aftermath is accurate, then it certainly is a shambles. I see no reason to question the script, as the delay in ordering the evacuation of Pripyat is truly damning.
They simply had no plans for such a catastrophe and the Soviet system did its usual blinkered management of their version of truth.
In fairness, I'm not convinced we would do much better if such an extreme event were to happen.
We came close.... Calder Hall.