Maybe he went to get Ichigo not for help but because he knew Inoue was involved. Both out of courtesy (dunno if Renji has such but anyway) and because if something happened, Ichigo would never forgive him otherwise. Well, I also thought it was a bit weak, but can't be helped. Maybe the Kurosaki house was suitably along the route to the Inoue house, and so it didn't cost any time.