Yoshitaka nodded in realization at Charlie's words—it was a simple plan, but he just wasn't thinking.
The mob bosses' authority after being sent to prison wasn't based on their influence before they were jailed, but on how much influence they still had after.
If Yoshitaka pressured their respective successors enough once Makoto and Yukihiro were incarcerated, their own successors might even send people into prison to kill them. Just making their lives difficult was way easier in comparison!
R