> How do you run the data centers during the night if they are solar powered?

A combination of battery storage and grid power, which is generally quite cheap overnight if current off-peak and on-peak pricing is any indicator.

I do not see any evidence that nuclear is quickly and economically deployable. The latest nuclear expansion to come online in the US took 15 years, 35 billion dollars, and resulted in power bill increases for customers to pay for that cost. If we can actually solve that it would be nice, but it hasn't been shown yet.

Neither of those get to the carbon neutral point of the whole endeavor. Just more complicated steps to shuffle the deck chairs around. Nuclear power is just magic rocks that get hot, put them in the water to make steam for the turbines. The costly part is a political and regulatory problem that is more easily solved than paving over all the farm land with solar panels or strip mining third world countries for lithium.