Not to mention that some people think Putin could attack other countries after Ukraine. That's not the time you want nuclear power plants as possible target.
If somebody attacks my region I would rather not like to worry about nuclear to be honest.
In any case, I have not heard of any fears that Russian missiles could damage Ukrainian wind or solar power plants.
Very difficult to interpret that fact when dealing with renewable-heavy grids. Germany probably doesn't have a lot of control over when the energy is being generated - so it is entirely possible that they are exporting but still reliant on electricity imports - if power is being produced when it is not needed.
This is an ecological concern, not a technical one. If the French are ok with frying fishes, they can let their nukes run.