Call for help what? This chapter came out a long time ago. And the author is perfectly fine. His wife just gave birth to their first baby a few months ago.
He is a minor, a child. And other Oni all lost people important to them so they all understood his decision to protect his sister as all cost. Some might do the same thing as him if they were in his situation.
Comparing this with real life is just ridiculous. Real-life doesn't have supernatural power that brainwashed you like Ukyo's. Also, Yusurube is literally a child, a minor. Even in real-life, child soldiers always got forgiven and sent to therapy and rehabilitation programs. I watched...
It has been mentioned many, many times. In the introduction arc, Mudano said that Jin's father is a Momo. In the Nerima arc, we got a whole flashback of Jin telling how his father killed his mother and sister because they were Oni. Jin's father pushed Jin to his limit to test whether he was Momo...
The fights in this are good. And there is no friendship BS. Shiki is actually near his limit already. He is just able to stand due to his anger and Kishin power. He wouldn't be able to win this if Tsukuyomi and Ousuke didn't appear.
You also should remember that most Oni lost their family so they understand and sympathize with Yusurube who is still just a kid. Most people would do anything fo save their family. No one can say for sure that they wouldn't do the same things as Yusurube to save their family.