It was really subtle. In those "aftermath" chapters, the only indication we had of Pell/Peru being alive was some dude (doctor, I think?) waving his hat in the air and telling him that he left it behind.>>11638221
As far as the people in Alabasta know, Nico Robin is still Miss All-Sunday, an agent of Crocodile's. I guess they're assuming she's still a bad guy of some sort?