Why a nuclear cargo ship might still avoid pump-jet propulsion

Could a nuclear-powered cargo ship use pump-jet propulsion?

Yes, but a less power-intensive propulsor would probably suit a commercial ship and allow a less demanding reactor plant.

The answer treats nuclear power and pump-jet propulsion as technically compatible rather than naturally inseparable. A cargo ship does not need the same acoustic or high-performance priorities as a submarine. A less power-intensive propulsor could permit a cooler, lower-pressure reactor arrangement and reduce plant complexity. The commercial design choice would therefore be driven by efficiency and operating burden, not by the novelty of pairing two advanced technologies.