People arguing for one alternative over the other are usually politically motivated. I feel like you are doing the same. Sometimes nuclear is a good fit, sometimes renewables is a good fit, sometimes fossil fuels are a good fit. Most of the time a mix is the best fit. It depends on what you are optimizing for and what is geographically, (geo)politically and economically possible. All these systems are then built using assumptions, sometimes those assumptions no longer make sense after a certain period of time and sometimes you just temporarily or permanently have to adapt to the changes in the environment. This is an unusual but expected scenario for the nuclear plants along the Danube.