Preventing people from playing in the realms they love for such a long time doesn't seem like a great way to improve retention.
A week, maybe... 6 months, though? Way too harsh.
Y'all always get hung on the minute details instead of the real point of the idea. It doesn't have to be 6 months, whatever, it can be whatever amount of time is decided would best. 5 minutes or 6 months, whatever passes "the giggle test" (whatever that is). The point was that you have a cooldown period where new people have the opportunity to take hold of the dead character's position and titles and thus when(if) replacement young character pops up it isn't so easy for him to just say "Hey I'm my father's son and he taught me everything he knew hand me all of his titles back."