One limitation is that these portable reactors need to be sited close to a large body of water.
That will restrict the deployment options significantly.
Why? The likely design is a natural convection sealed water moderator/cooler. Worst case total loss of coolant also removes the moderator, so shuts down the reactor; secondary fission in a reactor that size doesn't lead to meltdown. That's why one of the proposals for future civilian nuclear power generator is an array of modular reactors; inherently safe and highly redundant.