Does cooling the NAND chips on an SSD negatively affect its reliability?
The paper Influence of temperature of storage, write and read operations on multiple level cells NAND flash memories from 2018 shows the following graph, which suggests that writing to flash cells at a temperature of 25°C or lower results in earlier problems at reading compared to writing at 85°C.

In their discussion they deduce the following reasoning:


  Most NAND Flash memories implement the Fowler-Nordheim tunneling
  effect 1 in order to inject charges through the floating gate
  [7] during write operation. During write cycles, the programming
  circuit controls the charge of cells to ensure a sufficient margin of
  voltage threshold. It is assumed that the writing management circuit
  probably drifts with low temperatures. Indeed, transistor parameters
  (threshold voltage and gain) vary with temperature which in turn
  induces drain current shifts.  


And in the conclusion they summarize:


  Write operations at low temperatures lead to a decrease in
  data retention time, probably not due to a degradation of the cell but
  due to parametric drifts of the die embedded electronics dedicated to
  write operations.


This suggests why the comment cited in the question might say that.
But in practise I would assume that this effect is not relevant, because a better cooling of the flash will simply give the flash controller more headroom to higher performance while keeping the same temperature (assuming cooling with a traditional heatsink). After seeing the above measurements I would NOT cool my SSD with LN2, though.


https://doi.org/10.1016/j.microrel.2018.06.088