"Don't mock Captain Hero - a ticklish lesson for Kudo"
... and don't pull reckless stunts while fighting All For One's organization! These are the lessons Kudo, the second One For All holder, is learning the hard way.
I don't know much about Yoichi, Bruce and Kudo, so these interactions might be out of character in canon. However, I have read fanfictions where Yoichi, the first OFA holder, shows Captain Hero to Kudo and he often thinks it represents a parody of the hero genre. Also, in those fics he tends to find hero (an villains) monologues insufferables. On the other hand, I have read some fics where Kudo acts in a reckless and self-sacrificing way due to some issues. Consequently, I used all these elements to create this scenario inside the Void of One For All, where Kudo accidentally offends Captain Hero in front of Yoichi, who decides to punish him for this, with the help of Bruce, the third OFA user, who wants Kudo to pay for being a reckless sacrificing idiot and worrying both of them when they were alive.
In the end, I just wanted an excuse to draw the stony second OFA user laugh.