I think there might be an error or two here, though the fault is partly Livy's.
C Servilius, the triumvir taken by the Boii, does not appear to have taken the path of Pulcher to the plebeian caste. His son--listed in the Capitoline Fasti with the cognomen Nepos and not Geminus (as Livy would have it)--did serve as a plebeian aedile, but did so unaware of his father's existence, and a special rogatio was required to protect him from his illegal election to the tribuneship. This rogatio makes no sense if C Servilius had been plebeian.
For this reason, I don't really think that C Servilius should be counted as a precedent for the weird adoption to the plebeian caste by Caesar's Pretty Boy.
FWIW, over the 700 years that the Servilii served Rome, there were several patrician and plebeian branches, including Ahala, Axilla, Caepio, Casca, Geminus, Glaucia, Globulus, Priscus Fidenas, Rullus, Structus, Tucca, and Vatia Isauricus.