Spirit Cats had EI, IIRC Janis Nova Cat had it as a sign of her fanaticism . . . and like I said, they had enough resources in that area to go treat Julia.
Old warriors would not be worth it, you would have to retrain all their responses and skills. I do not think the Spirit Cats will show a age bias, they will have gone through a transformative process- the Fidelis threw off the bias to form their culture, and the Cats were already more accepting than any other Clan. The Nova Cats were one of the 3 Clans with a RAT for Protos in FM3085 with Satyr, Satyr XP, Roc, Roc 2, rare Roc 4, Gorgon, Chrysoar, Chrysoar 2 and Centaur as what they field . . . the amount of Satyr XP are interesting as they are tasked to support BA operations with SRMs. Roc is on there enough it should have a good representation.
I still think the Foxes maybe the supplier- for instance the Warden Wolves are known to use them but do not have a chart. I do not think we got anything specific saying the Foxes do not use them in small amounts- not like the confirmation the Crusaders, Falcons and Bears do not use them.