The main problem with solar and wind is that they can't be dispatched on demand. The power is incredibly cheap, but you are completely at the mercy of the weather.
What is needed is a source of power which can make up for the freak moments where 1) there isn't any sun, and 2) there isn't any wind, and 3) it lasts long enough that batteries can't cover it, and 4) it has to be widespread enough that you can't make up for it with power from half a continent away.
This power source will only need to be used for a few hundred hours per year but it'll need to carry a significant load, so while its per-MWh running costs are basically irrelevant its one-time per-MW construction costs should be fairly low.
This does not at all describe nuclear power, which has incredibly high construction costs, near-zero running costs, and is expected to run 24/7/365 at 100%.
The median reactor in the US produces 1-2GW. Most nuclear installations have multiple reactors, so capacity is a multiple of that. 1GW of solar generation requires literally millions of solar panels and thousands of acres of land, and still needs the transformers and distribution infrastructure. And that doesn't include any storage capability.
This is a contrived example. You're making it sound like solar is power available now. It simply isn't, on any scale like that. If it takes a decade to bring 1GW of solar online and two decades to bring 1GW of nuclear online, it's not as clear-cut.
Nuclear could be done a lot more quickly than it is and still be safe. Not as fast as solar, but it's not like it's an order of magnitude.