From a purely engineering perspective I think it becomes difficult to argue with the gas turbine once you get into the gigawatt class of data center. The amount of land required for this much solar is not to be understated. In many practical scenarios the solar array would need to be located a distance away from the actual data center. This implies transmission infrastructure which is often the hardest part of any electrical engineering project. You can put a gigawatt of N+1 generation on a 50 acre site with gas. It's dispatchable 24/7/365 and you can store energy for pennies on the dollar at incredible scale.

Having both forms of generation available at the same time is the best solution. Once you put a data center on the grid you can mix the fuel however you want upstream. This should be the ultimate goal and I believe it is for all current AI projects. I am not aware of any data center builds that intend to operate on parking lot generators indefinitely.

Sadly, I agree until we get SMRs (I think we are few years off). Obviously it would be more ideal to use grid+solar with curtailment but not super realistic.

they are talking about covering the desert with solar panels. why would you not put the data center in the middle of it?

If you have predictable demand at that scale, nuclear might make more sense than the combination of gas and solar.