Responses
Maybe the father knows something bad might happen to sabro if he became a demon king? Maybe something like being used by his uncle as a puppet demon king or something similar.
Maybe the father got threatened by the uncle and he cant tell sabro.
maybe something like not appropriate to become one, cuz in all honesty all he can think about is to become stronger nothing else
I wonder if there's a reason why the dad isn't positive about Sabro being a Demon king out of a sudden????