Zhang Zian understood that the police dog in Cage 5 suffered from PTSD, a type of mental illness.
Due to the long-standing disregard and prejudice against mental illnesses in China, even ordinary people would receive strange looks if they went to a therapist, as if they were patients with contagious diseases. No one pays attention to a dog's mental health. Whether it was SWAT, Fu Tao, or Old Yang, they all believed that this dog was a coward. These former police officers despised gutless humans and dogs.
PTSD and cowardice were not the same thing. The former was a disease, while the latter was a personality trait.
X's deeds were well known so no one would think that it was a gutless dog. However, X's training mainly took place in jungles. If it had received the urban anti-terrorism training and suffered the same explosion that Zhan Tian did, X's performance wouldn't be much better than Zhan Tian's.