I think it is an advantage, the question is just how big, and assume we look only at ongoing operation cost.

- Earth temperatures are variable, and radiation only works at night

- The required radiator area is much smaller for the space installation

- The engineering is simple: CPU -> cooler -> liquid -> pipe -> radiator. We're assuming no constraint on capex so we can omit heat pumps

Radiators on earth mainly do it to air, there's no air in space.