There is no obvious reason to believe that a coal or nuclear plant is any more reliable than, for example, a natural gas plant with firm transportation and/or fuel oil backup

I know a failed DOE bailout plan that begs to differ! But that failed for a reason

For sure the nuclear (and coal) plants have inherently superior reliability than other generation sources in normal operation conditions. Although abnormal meteorological conditions are rear events but it might happen.

"There is no obvious reason to believe that a coal or nuclear plant is any more reliable than, for example, a natural gas plant with firm transportation and/or fuel oil backup."

Duane Arnold shut down because the storm took down transmission lines that were providing power to the plant. A new 700 MWh gas plant in Marshalltown, IA without "black start" capability likely went offline temporarily, too - fuel source had nothing to do it.

The difference is Marshalltown generates 550,000 tonnes of CO2 emissions each year; Duane Arnold generates none.

The main difference of course is on-site fuel which both nuclear and coal have.   Most combined cycle plants do not maintain a fuel oil back due to the cost and complexity of this so we cannot be assured that they will have on-site fuel.  On-site distributed generation is one way to reduce the risk of transmission line damage when most of our generation remains concentrated in large generation facilities that the public does not want to see.