Data centers are not steady loads. Ramps can go from 10% to 100% in one to two minutes. Nuclear cannot keep up with that.
Small scale nuclear is more expensive than a large, 1 GW unit that, from my reading, is at peak thermal effcency to drive a gas turbine..
In addition, fuel for SMRs tends to be sourced from China or Russia as we don't make it here. (No one asks about that.)
Data centers have 10,000 plus nodes. Nodes. Memory, gpus, nodes, die just due to numbers, thermal cycling, throttling due to heat or load. They need to be diagnosed, fixed, replaced, tested, and brought back online. There is no steady load and that is what nuclear expects. Best case it's providing 10% or so of the load.