She kept crying in previous chapter.
Luffy's team kept running forward to the rooftop as every panel passes, means by last chapter Judge's son was still closer to Nami's position than now. He couldn't know Nami was in danger even when they were still in closer distance, let alone now when they're further separated.
Instead he was busy killing on more fodders, or more precisely, "rEdUcInG KaIdO's FoRcEs".
He really acted like a programmed robot, who wouldn't stop until he finished his programmed objective. Totally similar with random Germa clones who pulled a shield to cover Judge.