Thanks for your comment, Geron. Corporal punishment of children is a fraught issue. I'm hesitant to say much because of the strong feelings it arouses in many people--both advocates and opponents. I think in this story, there is a clear line between the abusive corporal punishment Dylan suffers and the mild corporal punishment in the Hicks family.
Having said that, I wouldn't argue that Sergeant Hicks' discipline is anything but wrongheaded and misguided, even in the context of fiction. His son, Trevor, treats it as a mild annoyance. It neither deters him from doing what he wants, nor does it make him examine his behavior. Hicks gains momentary compliance, but nothing more. It's a testament to the father-son bond that it doesn't harm their relationship. It's a testament to the Hickses' training by example that Trevor's transgressions are superficial rule breaking rather than moral turpitude or dangerous conduct.
Trevor's paddling, of course, serves as a device for Dylan to reveal the abuse he endured from his father. It also gives Hicks an opportunity to re-evaluate his own ideas of discipline, if for no other reason than to avoid triggering Dylan's PTSD.