But this chapter takes place during the reign of Claudius, who died in 54 A.D., well before Pliny's nephew was born, which is in 61 A.D. So this has to be the elder Pliny, which still makes no sense because this character was introduced as Caecilius Secundus, which is the name of Pliny's nephew
Unless I'm misrembering something the only time Pliny introduce himself in this volume is in chapter 72, where he says his name is Gaius Plinius Secundus, not Caecilius. You're not the only one who thought it was the younger though, so maybe you've misread his name because you were sure it was the younger.