One of the reasons why Oden decided to dance naked in the streets was to apologize to the Kurozumi Clan for the way they got treated by the people of Wano.
Orochi may be a scumbag but he and the rest of his family got persecuted and harrassed for no other reason than being related to the traitor who wanted to take over Wano (Orochi’s grandfather).
Kanjuro lost his will to live because he saw his parents getting murdered and Orochi only wanted to be shogun so he could have his revenge on what he perceived as a “collective guilt” of the Wano citizens.
In this way Orochi and Kanjuro are the same kind of victim that Ace was but they turned out different than Ace because your past doesn’t make you turn out good or evil, your choices do. It’s the same with Doflamingo and Rocinante. They had exactly the same past but one of them turned out good, the other one evil.
And if you look at Oden’s face while Orochi was telling his story to him you can see how he understands what Orochi had to go through and that he would have to take responsibility for that as the future shogun.
Let’s say the battle against Kaido is won and his son is in the hands of the Scabbards. They want to execute him just because he is Kaido’s son but Momonosuke steps in and forbids it because during his time on Onigashima he realized that Kaido’s son had nothing to do with his father’s crimes and is an entirely different person.
I believe this is how Momonosuke will be able to live up to his father. He is only eight and will never be as strong or brave like Oden, so instead of becoming the fighter Oden was he’ll become the person Oden was by sparing Kaido’s son and prevent any new reason for revenge on his part.
This will make him worthy of the title of Shogun. Not just in Wano’s eyes but in Luffy’s eyes as well.
It would also be in line with what Oda has already done with Ace, Doflamingo and Rocinante being persecuted for their heritage and the theme of Fishman Island which is basically “ending the cycle of revenge”.
*Theory by AgeofSmiles