Given that this captured thug has been taken into custody for assaulting a police officer, the guards already have a grudge against him. Notice how nervous the prisoner looks once he’s been rendered completely naked. It’s no wonder considering his body is now completely vulnerable to officers who, for all he knows, could be mates the policeman he assaulted earlier. The guard takes real satisfaction in getting him to bend over like an animal with his fully exposed arse sticking up in the air. They have mastered making men like this pose in humiliating positions while at all times remaining in charge and appearing courteous.