Characteristic advancement after character creation is via Dedication. The option to buy characteristics after this should be disabled. Consider a toggle to disable purchasing of characteristics with XP if total character XP exceeds XP on species.
I don't plan to implement this. You can tell your players not to spend it. The system is narrative, and generally the choice I've taken is to give the players the choice on how to do things.
Characteristic advancement after character creation is via Dedication. The option to buy characteristics after this should be disabled. Consider a toggle to disable purchasing of characteristics with XP if total character XP exceeds XP on species.