You'll note that a large proportion of these are due to the evacuation, and we do not know how much of that was necessary.
In terms of directly attributable health effects, including deaths, it's nowhere near the worst industrial disaster on record. It's a curious claim.
We'll likely never know whether that was due to the evacuation or simply that the risk were overstated. E.g. consider the Bhopal disaster [1] for comparison - 2259 official immediate deaths in Bhopal vs. 56, and nearly 4000 confirmed dead due to the disaster and 16k+ estimated total deaths, vs. a WHO estimate of 4000 eventual shortened lifespans after Chernobyl (e.g. people whose life expectancy over a period of decades is shortened due to increased cancer risks). Bhopal further caused an estimated 558,000 injuries.
For comparison, the Chernobyl exclusion zone used to be home to 120,000 people. Far more people were actually harmed in Bhopal than even lived near Chernobyl.
Chernobyl is only worse than Bhopal on a single measure: It will take longer before the area is fully safe to use again (but much shorter than people initially thought - as mentioned elsewhere, there is already pressure to open it up to more activity, as background radiation is already down to relatively safe levels).
[1] https://en.wikipedia.org/wiki/Bhopal_disaster